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A  MANUAL  OF 


ANATOMY 


IRVING  S.   HAYNES,  Ph.B.,  M.D. 

ADJUNCT    PROFESSOR    AND    DEMONSTRATOR    OF    ANATOMY    IN    THE     MEDICAL    DEPART- 
MENT OF  THE   NEW  YORK    UNIVERSITY  ;    VISITING   SURGEON  TO  THE    HARLEM 
hospital;      MEMBER     OF     THE    SOCIETY     OF     THE    ALUMNI     OF 
BELLEVUE   HOSPITAL,  OF  THE  AMERICAN  ASSOCI- 
ATION OF  ANATOMISTS,  ETC.,  ETC. 


TKIlitb  134  'Ibalf stone  tFllustrations  an&  42  Diagrams 


PHILADELPHIA 

W .     B .     SAUNDERS 

925  Walnut  Street 

1896 


Copyright,  1896,  by 
W.    B.    SAUNDERS 


TO 


LEWIS  A.  STIMSON,  B.A.,  M.D. 

PROFESSOR    OF  SURGERY  IN   THE   MEDICAL  DEPARTMENT    OF  THE 
NEW  YORK   UNIVERSITY 

THIS   SMALL  VOLUME   IS   OFFERED  AS  A  TRIBUTE 

OF    RESPECT    AND    AFFECTION 

BY  THE  AUTHOR 


PREFACE 


The  great  practical  importance  of  a  thorough  knowl- 
edge of  the  viscera  and  of  their  relations  to  the  surface 
of  the  body  has  been  recognized  in  preparing  this  Manual 
OF  Anatomy,  by  according  to  them  the  most  prominent 
place  in  illustration  and  description.  Further,  to  eluci- 
date their  formation  and  relations  in  the  adult,  a  brief 
histor}'  of  the  development  of  the  most  important  organs 
is  introduced. 

The  anatomy  of  the  extremities  has  been  treated  as 
fully  as  its  requirements  seem  to  demand. 

Descriptions  of  the  bones  and  the  joints,  and  of  those 
minute  parts  which  require  special  preparation  for  their 
dissection,  have  intentionally  been  omitted. 

Surgical  references  have  been  avoided,  except  in  a  few 
instances  where  it  seemed  advisable  for  the  student's  good 
to  suggest  the  application  of  a  process  or  a  description. 

The  descriptions  are  given  in  the  natural  order — that  is, 
the  order  in  which  the  structures  are  discovered  in  the 
dissection  ;  consequently  some  parts,  being  found  in  two 
or  more  regions,  receive  separate  notices,  but  cross-refer- 
ences are  freely  used  to  harmonize  such  descriptions. 

The  writer's  experience  as  a  teacher  in  anatomy  for 
several  years  is  utilized  in  stating  the  "facts  of  anatomy" 
which  have  been  gathered  from  the  standard  text-books 
on  this  and  the  allied  subjects.  Nothing  new  is  presented 
in  the  text  except  a  slight  contribution  touching  the  visceral 

11 


12  PREFACE. 

(thoracic  and  abdominal)  relations,  obtained  by  means  of 
"  composite  "  photographs.  Questions  of  theory  are  stated 
in  conformity  with  the  latest  published  opinions  of  recog- 
nized authorities ;  where  they  differ  from  previous  writers 
(for  example,  see  the  development  of  the  lamina  terminalis) 
both  opinions  are  expressed  and  the  more  rational  one 
indicated. 

All  the  illustrations  are  original,  and  excepting  a  few 
cases  are  from  photographs  by  the  author  of  his  own  dis- 
sections. Dissection  for  Fig.  72  was  made  by  Mr.  P.  D. 
Shultz ;  for  Figs.  80  and  81,  by  Mr.  J.  J.  Moorhead.  To 
these  gentlemen,  and  also  to  Messrs.  Asa  Iglehart  and  G. 
R.  Pisek,  for  their  efficient  assistance  in  the  preparation  of 
several  dissections  of  the  head  and  neck  and  the  upper 
extremity,  the  writer  gladly  expresses  his  thanks. 

The  diagrams  are  mostly  new  ;  those  copied  from  other 
text-books  are  duly  credited  to  their  proper  sources. 

Attention  is  invited  to  the  Index,  which  has  been  written 
up  from  the  beginning  of  the  proof-reading,  using  the  card 
system.  Every  reference  has  been  verified  from  the  com- 
pleted book,  and  no  pains  have  been  spared  to  make  this 
essential  feature  of  any  volume  complete,  comprehensive, 
and  accurate.  In  conclusion,  the  publisher  is  to  be  con- 
gratulated for  the  clearness  with  which  he  has  reproduced 
the  photographs,  and  for  the  care  and  neatness  displayed 
in  the  preparation  of  the  text. 

Irving  S.  Haynes. 

New  York,  May,  i8gb. 


CONTENTS 


PAGE 

THE  HEAD,  Anterior, 17 

Landmarks 17 

Craniocerebral  Topography,     17 

Dissection, 24 

Face,  Landmarks, 24 

Dissection, 28 

Skullcap,  Removal, 32 

Meninges,  Dissection, 32 

Brain,  Removal, 36 

Foss^  of  Skull,  Dissection, 36 

Orbit  and  Contents,  Dissection, 48 

Face,  Dissection, 58 

THE  NECK,  Anterior, 68 

Landmarks, 68 

Dissection, 69 

Deep  Face  and  Pharynx,  Dissection, 115 

Pharynx,  Dissection, 124 

HEAD  AND  NECK,  Posterior, 128 

Landmarks, 128 

Dissection, 128 

Pharynx,  Interior,  Dissection, 141 

Larynx,  Dissection, 145 

Nasal  Foss^,  Dissection, 148 

THE  BRAIN, 152 

Membranes, 152 

Dura, 152 

Arachnoid, , 154 

Pia, 156 

Blood  Supply, 158 

Development, 168 

Cerebrum, 178 

Base,      192 

Cranial  Nerves,  Superficial  (and  Deep),  Origin,    ....  198 

Cerebellum, 242 

13 


14  CONTENTS. 

PAGE 

THE  UPPER  EXTREMITY  AND  THORAX,  Anterior,  ....  255 

Landmarks, 255 

Outlining  Heart  and  Lungs  on  Chest  Wall, 258 

Shoulder,  Thorax,  and  Arm,  Dissection, 264 

Axillary  Space  and  Contents,  Dissection, 274 

Arm  and  Forearm,  Dissection, 282 

Palm  of  Hand,  Dissection, 300 

The  Brachial  Plexus,   .    .  ■ 312 

Thoracic  Viscera,    .   .   •: „ 319 

The  Heart, ."  .    .    .  330 

Removal  of  Heart  and  Lungs  from  Thorax, 343 

Heart,  Dissection, 352 

Lungs,  Dissection, 358 

THE  UPPER  EXTREMITY  AND  THORAX,  Posterior,  .    .       .360 

Landmarks  and  Dissection, 360 

Back  of  Arm,  Dissection, 365 

Back  (of  Trunk),  Dissection, '.  373 

SPINAL  CORD, 389 

Dissection, „ 389 

SPINAL  NERVES, 395 

THE  PERINEUM,  Male, .    •    •  397 

Landmarks, 397 

Fascia  of  Pelvic  Outlet, 398 

Dissection, 404 

THE  PERINEUM,  Female, 422 

External  Genitals, 422 

Dissection, 424 

THE  ABDOMEN,  Exterior, 432 

Landmarks, 432 

Regions, 435 

Dissection, ■  .    .    .  435 

The  Penis,  Dissection, 440 

The  Testicle,  Dissection, 443 

Abdominal  Rings,  their  Formation,  and  the  Formation 

of  the  Coverings  of  the  Cord  and  Testicle,    .  457 

THE  ABDOMEN,  Interior, 462 

The   Peritoneum,  Its    Development,  with   that  of  the 

AltmentaryCanal,  Liver,  Spleen,  and  Pancreas,  .  462 
The  Peritoneum,  Its  Reflections, 473 


CONTENTS.  15 

PAGE 

The  Abdominal  Viscera, 485 

Liver, 486 

Stomach, 494 

Intestine, 496 

Duodenum, 496 

Small  Intestine, 499 

Large  Intestine .  500 

Spleen, • 506 

Pancreas, 508 

Blood  Supply  for  the  Abdominal  Viscera, 509 

Kidneys, 522 

Suprarenal  Bodies, 524 

Ureters, 524 

The  Posterior  Abdominal  Wall, 525 

The  Lumbar  Plexus, 529 

The  Pelvic  Viscera,  Dissection, 536 

Bladder,      537 

Ureter, 540 

Vas  Deferens, 542 

Uterus,    . 542 

Ovary, 544 

The  Pelvic  Vessels, 546 

The  Interior  of  the  Bladder  and  Urethra, 550 

The  Sacral  Plexus, 551 

THE  LOWER  EXTREMITY,  Anterior, 554 

Landmarks, 554 

Dissection  of  the  Thigh, 556 

Dissection  of  the  Leg  and  Foot, 584 

THE  LOWER  EXTREMITY,  Posterior, 599 

Landmarks, 599 

Gluteal  Region  and  Thigh  Posterior,  Dissection,  .  .  .  599 
Popliteal  Space  and  Back  of  the  Leg,  Dissection,  .  .  616 
Sole  of  the  Foot,  Dissection, 634 


ADDENDUM, 648 

INDEX, , 649 


MANUAL  OF  ANATOMY, 


THE  HEAD,  Anterior. 

The  Landmarks. 

The  student  should  fully  investigate  the  landmarks  of 
the  head  with  especial  reference  to  the  subject  of  cerebral 
topography.  A  brief  resume  of  the  more  important  guides 
is  given  below.     See  Fig.  i. 

All  hair  should  be  shaved  or  carefully  clipped  from  the 
scalp  and  face. 

1)1  the  Median  Line. — The  nasion  is  the  centre  of  the 
nasofrontal  suture  and  is  marked  by  a  groove  at  the  root 
of  the  nose  where  it  joins  the  forehead. 

This  is  the  more  accurate  point  from  which  to  measure 
for  cerebral  localizations  than  from  the  point  usually  given, 
namely  the  glabella,  which  is  the  smooth  surface  between 
the  superciliary  ridges  and  abov'e  the  nasion. 

Next  the  bregma,  the  junction  of  the  coronal  and  sagit- 
tal sutures,  and  the  lambda,  the  intersections  of  the  sagit- 
tal and  lambdoid  sutures,  are  useful  anatomical  points  to 
remember. 

The  former  lies  half  an  inch  in  front  of  a  vertical  line 
drawn  upward  from  the  external  auditor^'  meatus,  the  latter 


2^  inches  above  the  inion. 


17 


18  A  MANUAL  OF  ANATOMY. 

The  inion  ;  this  is  another  name  for  the  external  occipital 
protuberance. 

Laterally. — The  supra-orbital  arch  is  the  prominent 
margin  bounding  the  orbital  cavity  above.  It  terminates 
internally  at  the  extremity  of  the  nasofrontal  groove  in 
the  obscure  internal  angular  process,  and  externally  in  the 
prominent  external  angular  process  (E.  A.  P.),  which  is 
one  of  the  very  useful  cranial  landmarks. 

The  zyg-omatic  arch  lies  horizontally  and  limits  the 
cranial  from  the  facial  regions.  It  also  corresponds  very 
nearly  with  the  lower  and  external  border  of  the  temporal 
lobe  of  the  brain. 

The  external  auditory  meatus  is  a  conspicuous  and 
useful  landmark  used  in  cranial  measurements,  as  it  is  both 
easily  felt  and  seen. 

The  parietal  eminence  is  more  of  an  area  than  a  point, 
but  it  is  useful  in  taking  general  measurements. 

The  mastoid  process  (its  tip  and  posterior  border), 
is  a  prominent  and  stable  landmark  in  the  adult,  but  in 
children  cannot  be  of  much  use  as  it  is  not  developed. 

The  superior  curved  line  of  the  occipital  bone  forms 
usually  a  readily  recognizable  ridge  arching  forward  from 
the  inion  to  the  base  of  the  mastoid  process.  It  determines 
the  boundary  between  the  back  of  the  head  and  neck. 

The  "  Sylvian  point "  is  the  point  upon  the  cranium 
which  indicates  where  the  Sylvian  fissure  reaches  the  ex- 
terior of  the  cerebrum. 

It  is  found  at  a  distance  of  one  and  one-quarter  inches 
directly  behind  the  external  angular  process  of  the  frontal 
bone. 

Relations  of  the  exterior  of  the  brain  to  the  surface 
of  the  cranium. 

The  margins  of  the  cerebral  hemispheres. 


^^' 


Fig.  I.    Cranio-Cerebral  Topography. 

1,  Median  line. 

2,  Superior  frontal  sulcus. 

3,  Inferior  frontal  sulcus. 

4,  5,  Fissure  of  Rolando. 

6,  Intraparietal  sulcus. 

7,  Parietal  eminence. 

8,  Main  part  of  fissure  of  Sylvius. 

9,  Vertical  limb  of  fissure  of  Sylvius. 

10,  Horizontal  limb  of  fissure  of  Sylvius. 

11,  Superior  temporal  sulcus. 

12,  Middle  temporal  sulcus. 

13,  13.  13,  i3i  Lower  border  of  the  cerebrum. 

14,  Zygomatic  arch. 

15,  Nasion. 

16,  Glabella. 


20  A  MANUAL   OF  ANA  TOMY. 

The  junction  of  the  vertical  with  the  external  surface  of 
a  hemisphere  is  indicated  by  a  line  drawn  from  the  nasion 
over  the  top  of  the  head  to  a  point  half  an  inch  external 
to  the  inion. 

This  line  when  drawn  on  both  sides  will  indicate  the 
position  of  the  superior  longitudinal  sinus. 

The  line  of  junction  of  the  inferior  and  external  surfaces 
of  the  cerebrum  is  indicated  as  follows  : 

Start  the  line  at  the  nasofrontal  groove,  and  carry  it  out- 
ward to  a  point  five-eighths  of  an  inch  (one-half  to  three- 
fourths  of  an  inch)  above  the  E.  A.  P.  ;  from  here  pass 
backward  to  the  Sylvian  point,  then  curve  a  line  downward 
and  forward  (with  its  concavity  backward  to  correspond  to 
the  rounded  extremity  of  the  temporal  lobe)  to  a  point  just 
above  the  junction  of  the  zygoma  with  the  frontal  process 
of  the  malar  bone.  (This  last  point  is  situated  one-fourth 
of  an  inch  above  the  zygoma  and  the  same  distance  from  the 
posterior  border  of  the  frontal  process  of  the  malar  bone. 
Or,  if  measured  from  the  E.  A.  P.,  it  is  a  vertical  line 
dropped  downward  from  a  point  five-eighths  of  an  inch 
posterior  to  the  E.  A.  P.  to  terminate  one-fourth  of  an  inch 
from  the  zygoma.)  Now  continue  the  line  backward  and 
slightly  downward  until  the  junction  of  the  zygomatic  arch 
with  the  skull  is  reached  (just  over  the  condyle  of  the 
inferior  maxilla).  The  line  then  inclines  upward  and  back- 
ward to  reach  a  point  one  inch  behind  and  half  an  inch 
above  the  level  of  the  external  auditory  meatus.  (This 
portion  of  the  line  passes  from  one-eighth  to  three-eighths 
of  an  inch  above  the  upper  margin  of  the  external  meatus 
and  intersects  a  vertical  line  drawn  upward  from  the  pos- 
terior border  of  the  root  of  the  mastoid  process,  one  inch 
behind  and  half  an  inch  above  the  external  auditory  meatus.) 

The  lower  posterior  border  of  the  cerebrum  is  finished 


THE  HEAD,   ANTERIOR.  21 

by  continuing  the  line  from  the  last  point  downward  and  back- 
ward to  the  inion,  following  for  the  posterior  two-thirds  of 
its  extent  the  superior  curved  line  of  the  occipital  bone. 

The  lower  border  of  the  cerebellum  is  indicated  by  a 
line  drawn  forward  and  downward  from  the  inion  to  the  pos- 
terior border  of  the  mastoid  process  at  its  base. 

The  Lateral  Sinus. — This  corresponds  to  a  band  one- 
fourth  of  an  inch  wide  extending  from  the  inion,  following 
the  curved  course  of  the  superior  nuchal  line  forward  to  a 
point  one  inch  directly  behind  the  external  auditory  meatus. 

The  Nasolambdoidal  Line. — This  is  a  line  connecting 
the  nasofrontal  groove  with  a  point  five-twelfths  to  five- 
eighths  of  an  inch  above  the  lambda. 

The  Fissure  of  Sylvius. 

Tlie  Horizontal  Portion. — This  is  indicated  by  drawing 
a  line  backward  and  slightly  upward  from  the  "  Sylvian 
point"  to  a  point  three-fourths  of  an  inch  below  the  most 
prominent  portion  of  the  parietal  eminence. 

The  posterior  two  inches  of  this  line  coincides  with  the 
nasolambdoidal  line. 

TJic  vertical  limb  of  the  Sylvian  fissure  corresponds  to  a 
line  one  inch  long  drawn  vertically  upward  from  the  hori- 
zontal limb  at  a  point  three-fourths  of  an  inch  from  its 
beginning,  or  two  inches  distant  from  the  E.  A.  P. 

The  Fissure  of  Rolando. — Take  57  per  cent,  of  the 
distance  from  the  glabella  to  the  inion,  or  (preferably)  five- 
sixths  of  an  inch,  behind  the  mid-point  between  the  nasion 
and  the  inion, — this  will  indicate  the  central  extremity  of 
the  fissure  of  Rolando. 

From  this  point  draw  a  line  three  and  three-eighths 
inches  long  downward  and  forward  so  as  to  make  an  angle 
with  the  median  line  of  71.5  degrees.      (Cunningham.) 


22  A  MANUAL  OF  ANA  TOMY. 

The  External  Portion  of  the  Parieto-occipital  Pis- 
sure. — This  is  five-twelfths  to  five-eighths  of  an  inch  in  front 
of  the  lambda,  or  one  and  seven-eighths  inches  behind  the 
central  extremity  of  the  fissure  of  Rolando,  and  extends 
about  an  inch  outward  and  slightly  forward  on  either  side 
of  the  median  line. 

The  Principal  Sulci. 

The  Frontal  Lobe. — The  superior  frontal  sulcus  is 

indicated  by  a  line  starting  from  the  supra-orbital  notch  (at 
the  inner  and  middle  thirds  of  the  supra-orbital  arch),  drawn 
backward  parallel  with  the  median  line  until  within  an  inch 
of  the  fissure  of  Rolando. 

The  inferior  frontal  sulcus  coincides  with  the  frontal  part 
of  the  temporal  ridge  (the  bony  not  the  muscular  ridge). 
It  begins  at  the  E.  A.  P.,  and  follows  the  curve  of  the  ridge 
upward  and  backward  until  within  an  inch  of  the  Rolandic 
fissure.  This  sulcus  is  parallel  with  and  about  an  inch 
from  the  preceding  one. 

The  superior,  middle,  and  inferior  convolutions  are 
thus  indicated,  and  the  region  in  front  of  the  fissure  of  Ro- 
lando and  an  inch  in  width  will  correspond  to  the  ascend- 
ing" frontal  convolution. 

The  Parietal  Lobe. — The  intraparietal  sulcus  is  shown 
by  drawing  a  line  from  a  point  one  inch  behind  the  fissure 
of  Rolando  and  the  same  distance  above  the  horizontal 
limb  of  the  Sylvian  fissure  upward,  one  inch  from  and  par- 
allel with  the  first  fissure,  until  at  the  junction  of  its  middle 
and  upper  thirds,  where  the  line  turns  backward  to  run 
parallel  with  the  middle  line,  and  about  an  inch  and  a  quar- 
ter from  it,  until  it  terminates  a  little  behind  the  parieto- 
occipital fissure  in  the  occipital  region.  The  space  behind 
the  fissure  of  Rolando  and  in  front  of  the  first  part  of  the 


Fig.  2.  Dissection  of  Head. — i,  Anterior  temporal  artery.  2,  Posterior  temporal 
artery.  3,  Temporal  artery.  Behind  it  is  the  auriculo-temporal  nerve.  4,  The  tem- 
poro-facial  division  of  the  facial  nerve  and  its  three  branches,  the  temporal,  malar,  and 
infra-orbital.  5,  Cervico-facial  division  of  the  facial  nerve,  and  its  three  branches,  the 
buccal,  supramaxillary ,  and  infraniaxillary .  6,  The  external  carotid  artery.  7,  The 
great  auricular  nerve.  8,  The  transverse  facial  artery.  9,  Anterior  part  of  Stenson's 
duct.     10,  Masseter  muscle.     11,  Facial  artery. 


24  A  MANUAL  OF  ANA  TOMY. 

intraparietal  line  is  the  ascending  parietal  convolution, 
the  region  between  the  second  part  of  the  sulcus  and  the 
median  line  is  the  superior  parietal  convolution,  and  the 
area  within  the  arch  of  the  intraparietal  sulcus  is  the  infe- 
rior parietal  convolution. 

The  Temporal  Lobe. — The  sulci  are  indicated  by  two 
lines  drawn  backward  and  upward  parallel  with  the  hori- 
zontal limb  of  the  fissure  of  Sylvius, — the  first  three- 
fourths  of  an  inch  from  the  Sylvian  fissure  and  the  second 
one  and  one-half  inches  from  the  same. 

The  first  temporal  convolution  corresponds  to  the 
region  between  the  Sylvian  fissure  and  the  first  sulcus,  the 
middle  convolution  to  the  area  between  the  first  and 
second  sulcus,  and  the  inferior  convolution  to  that  below 
the  last  sulcus. 

The  Occipital  Lobe. — This  agrees  with  the  area  behind 
the  parieto-occipital  fissure.  Its  divisions  into  convolutions 
is  by  incomplete  sulci,  and  both  convolutions  and  sulci 
are  unimportant. 

The  Region  of  the  Pace. — The  infra-orbital  arch  limits 
the  orbital  cavity  below.  It  leads  outward  to  the  malar 
bone,  which  varies  in  prominence  with  races  and  individuals. 
The  margins  of  the  lower  jaw,  posterior  and  lower,  and  the 
angle  (formed  by  their  junction)  can  easily  be  recognized. 
The  lower  border  of  the  jaw,  the  tip  of  the  mastoid  process, 
a  line  connecting  the  angle  of  the  jaw  with  the  tip,  and  the 
superior  curved  line  of  the  occipital  bone  form  the  arti- 
ficial and  natural  boundary  between  the  head  and  neck.  . 

DISSECTION. 
Support  the  head  properly  by  suitable  blocks  for  convenience  of  dissection. 
Incisions. — I.   From  the  root  of  the  nose  (nasion)  in  the  median  line  to  the 
occipital  protuberance  (inion). 


THE  HEAD,  ANTERIOR.  25 

2.  Horizontally  around  the  head  just  above  the  eyebrows  and  ears.  Be 
very  careful,  in  removing  the  skin,  not  to  take  with  it  the  underlying  muscles, 
which  are  closely  united  to  it  by  a  thin  layer  of  dense  fatty  tissue. 

Occipitofrontalis.      Fig.  2. 

Origin. — In  two  portions,  the  posterior  from  the  mastoid 
process  of  the  temporal  and  the  outer  two-thirds  of  the 
superior  curved  line  of  the  occipital  bones.  The  anterior 
portion  from  the  corrugator  supercilii,  pyramidalis  nasi,  and 
orbicularis  palpebrarum  muscles  with  which  it  is  continu- 
ous.     Also  from  the  overlying  integument. 

Insertio7i. — Both  bellies  are  attached  to  the  epicranial 
aponeurosis — galea  capitis — which  fills  in  the  space  left 
between  the  muscular  portions.  The  epicranial  aponeuro- 
sis also  reaches  over  the  side  of  the  head,  as  a  thin  layer 
covering  the  temporal  fascia,  and  gives  attachment  to  the 
small  superior  and  anterior  auricular  muscles. 

Nerve  Supply. — The  facial  or  seventh ;  the  posterior 
auricular  branch  supplying  the  occipital  portion,  and  the 
temporal  branches  the  frontal  portion  of  the  muscle. 

Action. — To  raise  the  eyebrows,  and  produce  transverse 
wrinkling  of  the  forehead. 

The  Auricular  Muscles. 

These  are  so  insignificant  as  to  scarcely  repay  the  atten- 
tion of  the  student,  and  their  description  is  omitted  here. 

The  Supratrochlear  and  Supra-orbital  Nerves.      Fig.  3. 

These  are  both  branches  of  the  frontal  branch  of  the 
ophthalmic  nerve.     See  page  49. 

The  supratrochlear  nerve  leaves  the  orbit  above  the 
pulley  of  the  superior  oblique  muscle  and  passes  to  the 
front  of  the  forehead,  supplying  the  skin  over  the  inner  third 
of  the  supra-orbital  arch. 

The  supra-orbital  nerve  issues  from  the  notch,  or  fora- 


26  A  MANUAL  OF  ANATOMY. 

men,  of  that  name,  and,  ascending  vertically  over  the  fore- 
head, is  distributed  to  the  integument  of  this  region  and 
the  anterior  portion  of  the  scalp. 

The  Frontal  and  Supra-orbital  Arteries.      Fig.  3. 

The  first  is  one  of  the  terminal  branches  of  the  ophthal- 
mic, the  second  a  branch  also  from  the  ophthalmic. 

The  frontal  accompanies  the  supratrochlear  nerve  (see 
above) ;  the  supra-orbital  the  nerve  of  the  same  name 
through  the  supra-orbital  foramen  to  the  distribution  of 
that  nerve. 

The  former  artery  anastomoses  with  the  opposite  frontal 
and  the  supra-orbital  arteries,  the  latter  with  the  frontal  and 
anterior  branch  of  the  temporal. 

The  Temporal  Artery.      Figs.  2  and  3. 

This  is  the  external  branch  of  bifurcation  of  the  external 
carotid.  It  starts  under  the  parotid  gland  at  the  neck  of 
the  lower  jaw,  passes  upward  and  over  the  zygoma,  and 
divides  into  the  anterior  and  posterior  temporal  branches. 
These  are  distributed  to  the  anterior,  lateral,  and  posterior 
portions  of  the  head.  The  anterior  anastomoses  in  front 
with  the  frontal  and  supra-orbital ;  the  posterior,  with  the 
posterior  auricular  and  occipital  arteries  ;  and  both,  over 
the  top  of  the  head,  with  the  corresponding  arteries  of  the 
other  side,  and  in  the  lateral  region  with  each  other.  For 
remaining  branches  see  page  62. 

Temporal  Branches  of  the  Facial,  and  Auriculotem- 
poral Branch  of  the  Fifth  Nerves.      Figs.  2,  3. 

For  the  former  see  the  facial  nerve,  page  61. 

The  auriculotemporal  branch  of  the  fifth  nerve  is  found 
(at  a  later  stage  of  the  dissection,  see  page  1 1 7)  to  arise  by 
two  roots  trunks,  which  surround  the  middle  meningeal 


Fig.  3.  Dissection  of  Head. — i,  Anterior  temporal  artery.  2,  Supra-orbital  artery 
and  nerve.  3,  Frontal  artery.  4,  Supratrochlear  nerve.  5,  Angular  artery.  6,  Infra- 
orbital artery  and  nerve.  7,  Lateralis  nasi  artery.  8,  Levator  anguli  oris  muscle. 
9,  Zygomaticus  major  muscle.  10,  Superior  coronary  artery.  11,  Inferior  labial  artery. 
From  this  is  given  off  the  inferior  coronary  artery.  12,  Mental  nerve  and  artery. 
13,  Termination  of  the  submental  artery.  14,  Temporal  fascia.  15,  Temporal  artery. 
i5,  Auriculo-temporal  nerve.  17,  Temporo-facial  division  of  the  facial  nerve.  18,  Sten- 
son's  duct  crossing  masseter  and  piercing  buccinator  muscles.  The  parotid  gland  is 
removed.  19,  Masseteric  artery  anastomosing  with  the  transverse  facial  and  infra- 
orbital.   20,  Facial  vein.    21,  Facial  artery. 


28  A  MANUAL  OF  ANATOMY. 

artery,  from  the  inferior  or  posterior  division  of  the  fifth 
nerve. 

Its  course  is  between  the  internal  lateral  ligament  and 
neck  of  the  lower  jaw,  then  between  the  temporomaxillary 
articulation  and  the  parotid  gland  ;  issuing  from  under  the 
gland,  it  turns  upward  along  with  the  temporal  artery,  be- 
hind which  it  runs  to  supply  the  integument  upon  the  side 
of  the  head. 

Its  branches  are,  also,  distributed  to  the  temporomaxil- 
lary articulation,  the  parotid  gland,  and  the  ear  (meatus  and 
upper  part  of  the  pinna). 

DISSECTION, 

Incision. — i.  Continue  the  median  incision  to  the  point  of  the  chin,  carry- 
ing it  around  the  wing  of  the  nose  and  the  angle  of  the  mouth. 

2.  From  the  last  point  extend  a  cut  backward  alo'ng  the  lower  border,  to  the 
angle  of  the  jaw  and  upward  to  the  lobe  of  the  ear. 

Reflect  the  flap  from  before  backward.  Much  care  will  have  to  be  exer- 
cised in  removing  the  integument  from  the  face,  as  it  is  very  thin,  especially 
so  over  the  eyelids,  and  closely  attached  to  the  facial  muscles,  which  are  thin, 
pale,  and  indistinct. 

Orbicularis  Palpebrarum.     Fig.  2. 

Origin. — The  palpebral  portion,  by  means  of  the  internal 
tarsal  ligament  (tendo-oculi)  from  the  crest  of  the  nasal 
process  of  the  superior  maxillary  bone. 

The  orbital  portion,  from  the  internal  tarsal  ligament,  the 
nasal  process  of  the  superior  maxilla,  and  the  inner  portion 
of  the  infra-orbital  arch. 

Insertion. — The  palpebral  portion,  into  the  external  tarsal 
ligament  and  by  it  into  the  front  of  the  frontal  portion  of 
the  malar  bone. 

The  orbital  portion  surrounds  the  palpebral  or  central 
portion  and  forms  the  sphincter  muscle  of  the  eyeHds. 
Insertion  same  as  the  origin. 


THE  HEAD,  AXTERIOR.  29 

Neme  Supply. — The  temporofacial  division  of  the  sev- 
enth nerve. 

Actio7i. — To  close  the  eyelids. 

The  Tarsal  Lig-aments. 

The  internal  is  a  fibrous  band  less  than  a  quarter  of  an 
inch  long  which  is  attached  internally  to  the  crest  of  the 
nasal  portion  of  the  superior  maxilla  and  externally  gives 
attachment  to  the  orbicularis  palpebrarum  muscle,  and  di- 
vides into  two  portions,  which  are  projected  into  the  mar- 
gins of  the  tarsal  cartilages. 

The  external  tarsal  ligament  passes  from  the  outer 
extremities  of  the  tarsal  cartilages  to  the  orbital  process  of 
the  malar  bone. 

Pyramidalis  Nasi. 

That  portion  of  the  occipitofrontalis  which  is  extended 
to  the  nasal  bones  where  they  are  joined  by  their  cartilages. 

The  compressor  narium,  depressor  al^  nasi,  dilator  naris 
anterior,  and  dilator  naris  posterior  are  muscles  of  interest 
to  the  specialist  in  the  field  of  anatomy  and  need  not  be 
dissected  by  the  student  (there  are  too  many  other  struc- 
tures of  more  importance  than  insignificant  muscles  of  this 
sort,  that  demand  his  attention). 

DISSECTION. 

Divide  the  aponeurosis  of  the  occipitofrontalis  in  the  median  line  and  also 
over  the  vertex  of  the  head  from  ear  to  ear. 

Reflect  the  anterior  triangular  portion  forward  and  downward  ;  when  near 
the  orbit  the  corrugator  supercilii  will  be  exposed.  By  turning  the  muscle 
still  further  downward  the  supra-orbital  notch  or  foramen  and  its  contents  will 
be  exposed. 

Reflect  the  posterior  half  of  the  occipitofrontalis.  The  temporal  fascia  is 
now  exposed.  After  learning  its  attachments  cut  it  away  from  its  upper  attach- 
ment, beginning  at  the  external  angular  process  of  the  frontal  bone,  and  turn 
it  downward. 

This  discloses  the  temporal  muscle. 


30  A  MANUAL  OF  ANATOMY. 

Corrug-ator  Supercilii. 

Origin. — From  the  inner  surface  of  the  superciliary  ridge 
of  the  frontal  bone. 

Insertion. — Into  the  inner  surface  of  the  frontal  portion  of 
the  occipitofrontalis  and  the  skin  above  the  middle  of  the 
eyebrow. 

Nerve  Supply. — The  seventh,  through  its  temporal 
branch. 

Action. — To  wrinkle  the  skin  of  the  forehead  vertically 
(frowning). 

The  Temporal  Fascia.     Fig.  3. 

This  is  a  dense  shiny  layer  of  fascia  lying  under  the  apo- 
neurosis of  the  occipitofrontalis,  and  covering  in  the  tem- 
poral muscle. 

It  is  attached  to  the  outermost  ridge  of  the  temporal 
fossa,  from  the  external  angular  process  of  the  frontal  to 
the  posterior  root  of  the  zygomatic  arch  behind,  and  below 
to  the  zygomatic  arch  in  two  layers,  one  to  the  inner  and 
one  to  the  outer  border  of  its  upper  margin. 

Between  these  layers  is  found  a  little  fat,  the  orbital 
branch  of  the  temporal  artery,  and  the  temporal  branch  of 
the  temporomalar  nerve  (of  the  superior  maxillary). 

Temporal.     Fig.  4. 

Origin. — From  the  whole  of  the  temporal  fossa  of  the 
skull  and  the  inner  surface  of  the  temporal  fascia. 

Insertion. — Into  the  tip,  anterior  border,  and  inner  sur- 
face of  the  coronoid  process  of  the  lower  jaw. 

Nerve  Supply. — The  fifth  cranial  nerve  through  the  motor 
portion  of  its  inferior  maxillar)-  branch. 

Action. — To  close  the  lower  jaw,  and,  by  the  posterior 
portion,  to  retract  it. 


Dissection  of  Head. — i,  Ridge  to  which  temporal  fascia  was  attached. 


rig-    4-        UISSECTION   OF    HEAD. — I,    MUge    lo    vvun-U    iciu|Juiai    ici3«.ia    vrco    cma^..v.v^ 

2  Stub  of  Steiison's  duct,  and  behind  it  the  buccal  branch  of  the  inferior  maxillary  nerve 
3'  Portion  of  the  facial  artery  resting  upon  the  buccinator  muscle.  4,  Temporal  muscle. 
5,  Anterior  auricular  artery.  From  the  side  of  the  temporal  artery  opposite  to  the 
anterior  auricular  is  seen  the  beginning  of  the  orbital  artery,  and  below  this  the  trans- 
verse facial.  6,  Deep  portion  of  the  masseter  muscle.  7,  External  carotid  artery. 
8,  Posterior  auricular  artery. 


32  A    MANUAL    OF  ANATOMY. 


DISSECTION. 

To  Retnove  the  Brain. — The  anterior  and  posterior  portions  of  the  occipito- 
frontalis  and  the  temporal  fascia  have  been  already  turned  down.  The  tem- 
poral muscle  is  now  to  be  dissected  from  its  attachment  to  the  temporal  fossa 
(the  deep  temporal  vessels  and  nerves  noted,  see  pp.  117,  121)  and  turned  over, 
or  cut  away  entirely  on  a  level  with  the  zygoma.  With  a  saw  the  outer  table 
of  the  skull  is  to  be  cut  through  in  a  line  from  a  point  three-fourths  of  an  inch 
above  the  supra-orbital  arches  to  the  occipital  protuberance,  completely  en- 
circling the  head. 

When  the  outer  table  has  been  cut  through,  as  is  shown  by  the  bloody  saw- 
dust turned  out,  the  saw  is  to  be  changed  for  a  chisel.  The  ordinary  "  cold  " 
chisel  is  suitable  for  this  purpose.  With  a  chisel  break  off  the  skull-cap, 
entering  the  chisel  first  at  the  external  angular  processes  of  the  frontal  bone, 
then  over  the  mastoid  processes.  Be  careful  not  to  drive  the  chisel  through 
into  the  brain.  After  breaking  the  skull  at  these  four  points,  the  entire  top  of 
the  skull  will  probably  be  loosened. 

Insert  a  strong  hook  at  the  forepart  of  the  skull-cap,  and  with  a  sharp, 
quick  pull  tear  it  from  the  dura. 

Before  going  farther  study  the  middle  meningeal  artery  and  dura. 

For  the  artery  see  page  44. 

The  Dura.     Figs.  6  and  8. 

The  dura  is  the  most  external  membrane  which  envel- 
ops the  brain.  It  is  closely  applied  to  the  inner  surface 
of  the  cranium  and  forms  the  inner  periosteum  for  the  bones 
which  compose  it. 

This  attached  surface  is  rough,  as  will  be  seen  after  the 
skull-cap  has  been  removed.  The  inner  surface  of  the  dura 
is  smooth,  and  is  in  close  relation  to  the  arachnoid  (see 
page  I  5  2),  from  which  it  is  separated  by  the  smallest  inter- 
val, called  the  subdural  space. 

Offsets  from  the  inner  layer  of  the  dura  are  found  in  cer- 
tain places,  as  between  the  halves  of  the  cerebrum — the  falx 
cerebri,  between  the  cerebrum  and  cerebellum — the  ten- 
torium cerebelli,  and  between  the  two  lobes  of  the  cere- 
bellum— the  falx  cerebelli. 

Along  the  lines  where  these  offsets  take  place  spaces  are 


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34  A   MANUAL  OF  ANATOMY. 

left  between  the  two  layers  of  the  dura  called  the  cranial 
sinuses.  These  sinuses  are  also  found  at  other  points  than 
where  these  processes  are  given  off,  as  at  the  base  of  the 
skull.     The  sinuses  will  follow  later  ;  see  below. 


DISSECTION. 

Split  open  the  superior  longitudinal  sinus  from  its  beginning  to  its  ending, 
and  in  doing  so  notice  the  cords  which  cross  it.  These  are  the  chordae 
Willisii. 

Divide  the  dura,  just  above  the  bone,  entirely  around  the  head.  Raise  the 
dura  from  the  brain  and  turn  it  upward  at  the  sides  as  far  as  possible  ;  this 
will  expose  the  attachment  of  the  falx  cerebri. 

The  falx  is  to  be  cut  from  its  attachment,  and  with  the  dura  turned  back- 
ward. Divide  the  cerebral  veins  when  encountered,  and  turn  the  dura  off 
backward  from  the  brain,  exposing  its  upper  surface.  As  a  rule  the  dura  is 
not  removed  far  enough  backward. 

In  the  free  margin  of  the  falx  will  be  seen  a  very  small  opening,  looking 
like  a  slit.     This  is  the  inferior  longitudinal  sinus. 

The  Falx  Cerebri.     Figs.  8  and  9. 

This  is  a  sickle-shaped  process  of  the  dura  which  lies 
between  the  two  cerebral  hemispheres.  It  is  attached  all 
along  its  base  to  the  dura  (with  which  it  is  continuous)  and 
at  its  attachment,  by  the  divergence  of  its  layers  is  formed 
the  superior  longitudinal  sinus.  See  below.  Its  anterior 
extremity  is  fastened  to  the  crista  galli,  and  its  posterior 
extremity  to  the  upper  surface  of  the  tentorium  cerebelli. 
At  this  rear  attachment  the  straight  sinus  is  formed  by  the 
separation  of  its  layers,  similar  to  the  formation  of  the  su- 
perior sinus. 

The  Superior  Longitudinal  Sinus.      Diag.  i.     Fig.  8. 

As  stated  above,  this  sinus  is  formed  at  the  base  of  the 
falx  cerebri,  where  its  two  layers  pass  off  laterally  into  the 
inner  layer  of  the  dura. 


THE  HEAD,  ANTERIOR. 


35 


It  will  be  found  to  extend  from  the  foramen  caecum  in 
the  frontal  bone  over  the  convexity  of  the  head  in  the  mid- 
dle line,  and  at  the  base  of  the  falx  cerebri  (as  will  be  ap- 
parent later),  to  terminate  in  a  considerable  cavity  opposite 
the  external  occipital  protuberance,  called  the  torcular 
Herophili,  or  the  confluence  of  sinuses  ;  or  it  may  pass  into 


Diag.  I.  A  Diagram  of  the  Sinuses  of  the  Skull,  Vertical-antero-poste- 
RiOR.  (/.  S.  H,)—i,  Superior  longitudinal.  2,  Inferior  longitudinal.  3,  Straight.  4, 
Lateral.  5,  Cavernous.  6,  Superior  petrosal.  7,  Inferior  petrosal.  8,  Internal  jugu- 
lar vein,  formed  below  the  skull  by  the  junction  of  the  inferior  petrosal  and  lateral 
sinuses.  9,  Right  and  left  veins  of  Galen.  10,  Common  vein  of  Galen.  11,  Occipital. 
12,  Foramen  magnum.    13,  Jugular  foramen. 


the  right  lateral  sinus  (usual).  By  the  scissors  this  sinus  is 
to  be  laid  open  from  its  beginning  to  its  ending.  The  bands 
crossing  the  sinus  are  the  chordae  Willisii.  Its  tributaries 
are  the  nasal  veins  (sometimes)  through  the  foramen  caecum, 
the  parietal  through  the  parietal  foramen,  the  superior  cere- 


36  A   MANUAL   OF  ANATOMY. 

bral.     These  will  be  found  passing  to  the  sinus  over  the  top 
of  the  brain. 

The  Inferior  Longitudinal  Sinus.      Diag.  i.      Fig.  8. 

This  is  a  small  slit  left  between  the  two  layers  of  the  dura 
composing  the  falx  cerebri  at  its  free  margin.  It  extends 
from  the  anterior  and  middle  third  of  the  falx  to  its  attach- 
ment to  the  tentorium,   where  it  opens  into  the    straight 

sinus, 

DISSECTION. 

Raise  the  neck  with  a  block,  let  the  head  (and  with  it  the  brain)  drop 
backward,  supporting  the  brain  that  it  does  not  draw  too  forcibly  upon  its 
basal  attachments. 

Gently  insert  the  fingers  of  one  hand  between  the  brain  and  the  dura,  sepa- 
rating the  former  from  the  latter,  until  the  olfactory  nerves  are  seen.  Raise 
these  from  the  groove  in  the  bone  with  the  handle  of  a  knife  ;  they  will 
usually  remain  attached  to  the  brain.  Let  the  brain  sag  backward  until  the 
optic  nerves  come  into  sight ;  divide  these  close  to  the  bone  and  the  internal 
carotid  artery,  which  will  be  seen  at  the  same  place. 

The  infundibulum  is  now  seen  extending  to  the  pituitary  gland,  located 
within  the  sella  turcica.  To  remove  the  gland  cut  through  the  dura  covering  the 
cavity  containing  it,  and  with  the  handle  of  the  knife  turn  the  gland  out  of  its  bed. 

Still  let  the  brain  fall  backward  and  cut  through  the  third,  fourth,  fifth,  and 
sixth  nerves. 

Cut  the  tentorium  along  the  anterior  attachment  (to  the  superior  border  of 
the  petrous  portion  of  the  temporal  bone) .  This  will  free  the  brain  so  that  all 
the  remaining  nerves  can  be  divided  close  to  the  bone. 

The  last  step  is  now  the  most  important.  Carefully  cut  through  the  verte- 
bral arteries  upon  either  side  of  the  cord,  and  finally  divide  the  cord  across  as 
low  as  possible. 

The  brain  is  now  free,  except  its  attachment  by  the  vein  of  Galen  to  the 
straight  sinus;  divide  this,  after  replacing  the  brain,  by  separating  its  hemi- 
spheres and  cutting  through  the  veins  just  in  front  of  the  tentorium. 

Remove  the  brain  and  place  it  in  a  solution  of  alcohol  (60  per  cent.)  and 
chloride  of  zinc  (added  to  the  alcohol  until  the  brain  floats  midway  between 
the  top  and  bottom  of  the  vessel ;  this  will  insure  that  when  the  brain  is  har- 
dened it  will  preserve  its  normal  outlines.  With  this  solution  the  pia  need  not 
be  removed  until  the  brain  is  to  be  dissected,  though  it  had  better  be  removed 
in  the  course  of  the  first  week.  For  complete  hardening  of  the  brain  in  this 
solution  about  three  weeks  is  needed).  For  the  dissection  of  the  brain  see 
page  152. 


V. 


Rjp.  7.       CRAinO-CEREBRAI.   TOPOGRAPHY. 

1,  I,  Fissnre  of  Rolando. 

2,  Fissme  of  Sjrlrhis,  main  pottioa. 

3,  Vertical  linib  of  same. 

4,  Horizootal  limb  of  same. 

5,  latnqnrieCal  salens.    For  the  remaining  fissures,  sulci,  and  convolutions  consult 
Fig.  23. 

6,  Skin. 

7,  Bone. 

8,  Don. 


38  A  MANUAL   OF  ANA  TOMY. 

Now  study  the  parts  at  the  base  of  the  skull.      Fig.  lo. 

The  base  of  the  skull,  internally,  is  divided  into  three 
fossae — the  anterior,  middle,  and  posterior. 

The  anterior  fossa  has  for  its  floor  the  orbital  plate  of 
the  frontal,  the  cribriform  plate  of  the  ethmoid,  and  the  les- 
ser wings  of  the  sphenoid  bones. 

The  posterior  margin  of  the  last  and  the  optic  groove 
bounds  the  fossa  posteriorly. 

The  Middle  Fossa. — This  is  the  central  hollow,  and  its 
floor  is  composed  of  the  greater  wings  and  body  of  the 
sphenoid  and  the  front  surfaces  of  the  petrous  portions  of 
the  temporal  bones.  The  fossa  is  limited  behind  by  the 
superior  margin  of  the  petrous  portions  of  the  temporal 
bones  and  the  dorsum  ephippii.  Anteriorly,  by  the  lesser 
wings  of  the  sphenoid  and  optic  groove. 

The  posterior  fossa  of  the  skull  is  all  that  portion  of  the 
base  internally  which  extends  behind  the  superior  margins 
of  the  petrosal  bones  and  the  dorsum  ephippii. 

The  contents  of  these  various  fossae  will  be  apparent  as 
the  dissections  of  the  floor  of  the  cranial  cavity  proceeds. 

The  Tentorium  Cerebelli.     Fig.  9. 

This  is  a  portion  of  the  dura  which  lies  between  the 
cerebrum  and  the  cerebellum.  It  is  attached  externally  to 
the  dura  (and  so  to  the  bone)  along  the  line  of  the  lateral 
sinuses  (which  it  forms  by  the  separation  of  its  layers). 
Internally  it  is  attached  to  the  superior  border  of  the  pe- 
trous portion  of  the  temporal  bone  (enclosing  the  superior 
petrosal  sinuses  at  this  point),  and  to  the  posterior  and 
anterior  clinoidal  processes. 

An  opening  is  left  between  the  petrosal  attachments 
through  which  the  crura  cerebri,  basilar  artery,  and  third 
and  fourth  nerves  pass. 


40 


A  MANUAL  OF  ANA  TOMY. 


The  Palx  Cerebelli.     Fig.  lo. 

This  is  the  small  ridge  of  dura  placed  between  the  two 
lobes  of  the  cerebellum  and  extending  from  the  under  sur- 
face of  the  tentorium  in  the  middle  line  to  the  posterior 
margin  of  the  foramen  magnum. 

The  Straight  Sinus.     Diags.  i  and  2. 

This  will  be  found  by  slitting  up  the  attachment  of  the  falx 

cerebri  to  the  tentorium.      It  is  contained  or  formed  by  the 

diverging  halves  of  the 
falx  at  its  tentorial  at- 
tachment. It  extends 
from  the  anterior  (free) 
margin  of  the  tentorium, 
where  it  receives  the 
inferior  longitudinal 
sinus  and  the  vein  of 
Galen,  backward  to  end 
in  the  torcular  Herophili, 
or  be  continued  into 
one  of  the  lateral  (usually 
the  left)  sinuses. 

The  Lateral  Sinuses. 
Diags.  I  and  2. 
Fig.  10. 

Diag.  2.    A  Diagram  of  the  Sinuses  at  . 

THE  Base  of  the  Skull.    {I.S.H.)—i,   Cavern-  These        run       m       the 

ous.    2,  Superior  petrosal.    3,  Inferior  petrosal,  attached    margins   of  the 

4,  and  5,  Lateral.    6,  Circular.     7,  Transverse,  ° 

(more  of  a  plexus).     8,  Communicating  between  tentorium  from  the  intcr- 

the  lateral  and  9,  Occipital  sinuses.    10,  Foramen  ,               •    •,    1               .     i_ 

magnum.  "al    occipital    protuber- 

ance behind  to  the 
petrous  portion  of  the  temporal  bone,  where  they  turn  down- 
ward through  the  sigmoid  groove  of  the  temporal  bone  to 
pass  through  the  posterior  compartment  of  the  jugular  fora- 
men and  terminate  in  the  internal  jugular  vein,  g.  v.,  page  92. 


Fig.  9.  Interior  of  the  Base  of  the  Skull,  Tentorium  in  Place. — i,  Crista 
galli  and  atlachmeiit  of  falx  cerebri.  2,  Olfactory  bulb.  3,  Optic  nerve.  4,  Middle  cere- 
bral artery.  5,  Posterior  communicating  artery.  6,  Infundibuluni  and  jiituitary  gland. 
7,  Third  nerve.  S,  Posterior  cerebral  artery.  9,  Crusta  of  crus  cerebri.  10,  Tegmentum 
of  same.  Between  them  is  the  locus  niger.  11,  Attachment  of  the  falx  cerebri  divided 
close  to  the  tentorium  cerebelii.     12,  Lateral  sinus.     13,  Tentorium  cerebelli. 


42  A  MANUAL  OF  ANATOMY. 

The  right  lateral  sinus  usually  receives  the  superior 
longitudinal  sinus ;  while  the  left  receives  the  straight 
sinus,  and  the  two  are  connected  by  a  short  sinus  across 
the  internal  occipital  protuberance. 

In  other  cases  the  four  sinuses  open  into  a  common 
cavity  termed  the  torcular  Herophili — or  the  confluence  of 
sinuses.  The  lateral  sinuses  also  receive  the  veins  from 
the  posterior  part  of  the  cerebrum,  the  upper  and  lower 
surfaces  of  the  cerebellum,  from  the  diploe,  also  the  su- 
perior petrosal  sinuses.  They  communicate  with  external 
veins  through  the  mastoid  and  posterior  condyloid  fora- 
mina. 

The  Superior  Petrosal  Sinus.     Diags.  i  and  2. 

Two  in  number,  one  on  either  side.  This  sinus  is 
located  in  a  groove  along  the  upper  margin  of  the  petrous 
portion  of  the  temporal  bone  (the  tentorium  being  attached 
to  the  margins  of  the  groove).  Externally  it  opens  into 
the  lateral  sinus,  and  internally  into  the  cavernous  sinus. 

The  Occipital  Sinus.     Diags.  i  and  2. 

Is  formed  by  the  junction  of  the  marginal  sinuses  at  the 
posterior  part  of  the  foramen  magnum.  It  extends  upward 
in  the  median  Hne  to  open  into  the  confluence  of  sinuses 
over  the  internal  occipital  crest.  The  marginal  sinuses 
communicate  in  front  with  the  lateral  sinuses. 

The  Inferior  Petrosal  Sinus,  (A  paired  sinus.)  Diags.  i 
and  2. 
It  extends  backward  from  the  cavernous  sinus,  at  the 
margin  of  the  basilar  process  of  the  occipital  bone,  to 
leave  the  skull  through  the  anterior  compartment  in  the 
jugular  foramen,  and  below  the  margin  of  the  foramen  helps 
to  form  the  internal  jugular  vein  by  joining  with  the  lateral 
sinus. 


THE  HEAD,  ANTERIOR. 


43 


The  Cavernous  Sinus.     Diags.  i  and  2.      Fig.  10. 

Two,  one  on  either  side  of  the  body  of  the  sphenoid 
bone. 

It  extends  from  the  inner  extremity  of  the  sphenoidal 
fissure,  where  it  receives  (is  really  the  continuation  of)  the 
ophthalmic  vein  from  the  orbit,  to  the  apex  of  the  petrous 
portion  of  the  temporal  bone,  where  it  terminates  in  the 
superior  and  inferior  petrosal  sinuses. 


Diag.  3.  A  Diagram  of  the  Cavernous  Sinus.  (/.  5.  //^^)— The  diagram 
shows  the  right  sinus  divided  transversely  and  its  cavity  filled  with  fine  interlacing 
trabeculae.  i,  Ophthalmic  division  of  the  fifth  cranial  nerve.  2,  Fourth  cranial  nerve. 
3,  Third  cranial  nerve.    4,  Sixth  cranial  nerve.    5,  Internal  carotid  artery. 


The  cavernous  sinuses  are  connected  across  the  sphenoid 
bone  by  the  circular  sinus. 

Upon  the  inner  wall  of  the  cavernous  sinus  is  the  inter- 
nal carotid  artery  and  the  sixth  nerve ;  on  the  outer  wall 
the  third,  fourth,  and  ophthalmic  division  of  the  fifth  nerves  ; 
all  these  structures  are  separated  from  the  blood  in  the 
sinus  by  a  covering  of  endothelium. 


44  A  MANUAL  OF  ANA  TOMY. 

The  Circular  Sinus.     Diag.  2. 

Connects  the  two  cavernous  sinuses  in  front  and  behind 
the  pituitary  body,  which  it  encloses  in  a  venous  circuit. 

The  Transverse  Sinus.     Diag.  2. 

This  is  really  a  venous  plexus  upon  the  basilar  process 
of  the  occipital  bone,  joining  the  two  inferior  petrosal  si- 
nuses and  communicating  with  the  spinal  veins  below. 

DISSECTION. 

Trace  out  the  middle  meningeal  artery,  noting  how  deeply  its  trunk  and  the 
beginning  of  the  anterior  and  posterior  branches  groove  the  bone,  sometimes 
being  bridged  over  with  bone  at  the  anterior  inferior  angle  of  the  parietal 
bone. 

Clean  the  stumps  of  the  second  to  twelfth  cranial  nerves  from  before  back- 
ward and  learn  their  foramina  of  exit. 

Trace  the  nerves  and  internal  carotid  artery,  which  pass  through  the  caver- 
nous sinus,  and  follow  the  carotid  artery  until  it  disappears  through  the  middle 
lacerated  foramen. 

The  Gasserian  ganglion  is  to  be  carefully  exposed,  and  the  three  branches 
of  the  fifth  nerve  shown. 

The  contents  of  the  jugular  foramen  are  to  be  separated  and  learned.  They 
are  the  glosso-pharyngeal,  pneumogastric,  and  spinal  accessory  nerves,  occu- 
pying the  central  compartment ;  the  inferior  petrosal  sinus,  the  anterior  com- 
partment; and  the  lateral  sinus,  the  posterior  compartment. 

The  Middle  Meningeal  Artery.     Figs.  6  and  10. 

This  artery  within  the  skull  is  found  coming  through 
the  foramen  spinosum  and  grooving  the  inner  surface  of 
the  skull  as  it  winds  upward  and  backward. 

It  divides  into  two  principal  branches,  the  anterior  and 
posterior  meningeal.  These  between  them  supply  the  ante- 
rior, lateral,  and  posterior  areas  of  the  skull  and  dura. 
For  the  origin  of  the  artery  see  page  121. 

The  anterior,  small,  and  posterior  meningeal  arteries 
are  very  small,  and  will  not  repay  any  time  expended  upon 
their  dissection.     The  anterior  are  furnished  by  the  ethmoi- 


Fig.  lo.    Interior  of  the  Base  of  the  Skull,  Tentorium  Removed. 
I  to  12,  The  various  cranial  nerves  at  their  foramina  of  exit. 

13,  Pituitary  gland  and  infundibulum. 

14,  Spinal  cord. 

15,  Internal  carotid  arter>-. 

16,  Lateral  sinus. 

17,  Middle  meningeal  artery. 

18,  Cavernous  sinus  opened.    Figure  5  points  to  the  Gasserian  ganglion  on  the  fifth 
nerve.    A,  anterior,  £,  middle,  C,  posterior  fossa  of  skull. 


46  A  MANUAL  OF  ANA  TOMY. 

dal  and  the  internal  carotid  ;  the  posterior,  by  the  ascending 
pharyngeal,  occipital,  and  vertebral ;  the  small  meningeal 
is  supplied  to  the  Gasserian  ganglion  and  parts  of  dura 
adjacent  thereto  ;  it  enters  the  skull  through  the  foramen 
ovale. 

Structures  Passing  Through  the  Sphenoidal  Fissure. — The 
third,  fourth,  sixth,  and  ophthalmic  branch  of  the  fifth  cranial 
nerves,  the  sympathetic  nerve,  the  orbital  branch  of  the 
middle  meningeal  artery  and  a  recurrent  branch  from  the 
lachrymal,  and  the  ophthalmic  vein. 


Diag.  4.  A  Diagram  of  the  Sphenoidal  Fissure.  (/.  6'.  H.) — i,  Lachrymal 
nerve.  2,  Frontal  nerve.  3,  Fourth  cranial  nerve.  4,  Superior  division  of  third 
cranial  nerve.  5,  Nasal  nerve.  6,  Inferior  division  of  third  cranial  nerve.  7,  Sixth 
cranial  nerve.    8,  Ophthalmic  vein. 


If  great  care  is  used  the  great  petrosal  nerve  may  be 
found  extending  from  the  hiatus  Fallopii  (see  a  dry  skull) 
forward  and  inward,  to  disappear  beneath  the  Gasserian 
ganglion.     See  Facial  Nerve. 

The  Gasserian  g-anglion  and  beginning  of  the  trunks 
of  the  three  divisions  of  the  fifth  cranial  nerve.  Figs.  lo 
and  II. 


(From  a  preparation  in  the  Museum  of  the  University  Medical  College.) 
Fig.  II.    The  Course,  Relations,  and  Distribution  of  the  Cranial  Nerves.— 

I,  Optic  nerve.  2,  The  internal  carotid  artery.  3,  The  sixth  cranial  nerve.  4,  Third 
cranial  nerve.  5,  Fourth  cranial  nerve.  6,  Fifth  cranial  nerve,  with  the  Gasserian 
ganglion.  Its  divisions  into  the  ophthalmic,  superior  maxillary,  and  inferior  maxil- 
lary branches  is  clearly  shown.  The  course  of  these  branches  with  their  terminal 
divisions  or  distributions  can  easily  be  traced.  To  indicate  each  small  branch  on  the 
photograph  would  ruin  it.  7,  The  facial  nerve.  The  geniculate  ganglion  and  branches, 
the  chorda  tympani  (passing  downward  and  forward  to  join  the  gustatory-  nerve),  and  the 
terminal  divisions  and  their  branches  are  all  shown.  8,  Spinal  accessory  passing  upward 
to    the    foramen    magnum.     9,  Same    nerve    in    the    neck.      10,  Pneumogastric    nerve. 

II,  Glosso-pharyngeal  nerve.  12,  Internal  carotid  artery.  Notice  the  various  sympa- 
thetic plexuses  upon  it.  13,  Superior  cervical  ganglion.  14,  Ophthalmic  ganglion. 
15,  Supra-orbital  nerve.  16,  Lachrymal  gland.  17,  Meckel's  ganglion.  18,  Infra-orbital 
nerve.  19,  Mental  nerve.  20,  Internal  pterygoid  muscle.  21,  Frontal  sinus.  The 
student  is  urged  to  study  the  relations  within  the  orbit  and  the  three  great  trunks  of  the 
fifth  nerve. 


48  A  MANUAL   OF  ANA  TO  MY. 

The  Gasserian  ganglion  is  developed  upon  the  sensory- 
portion  of  the  fifth  nerve,  and  lies  in  a  shallow  depression 
upon  the  antero-superior  surface  of  the  apex  of  the  petrous 
portion  of  the  temporal  bone.  The  ganglion  receives  sym- 
pathetic filaments  from  the  carotid  plexus. 

From  the  anterior  margin  of  the  ganglion  three  trunks 
composed  of  sensory  fibres  are  given  off.  The  upper  one 
is  the  ophthalmic  branch,  which  traverses  the  cavernous 
sinus  and  takes  its  exit  from  the  skull  through  the  sphe- 
noidal fissure,  the  middle  is  the  superior  maxillary,  which 
leaves  through  the  foramen  rotundum,  and  the  third  branch 
is  the  inferior  maxillary,  which,  with  the  motor  root, 
descends  through  the  foramen  ovale  ;  these  two,  being 
joined  external  to  the  skull,  form  the  inferior  maxillary 

nerve. 

DISSECTION  OF  THE  ORBIT. 

If  the  skull  is  to  be  preserved  intact  the  contents  of  the  orbital  cavity  are  to 
be  removed  as  follows  : — 

Cut  through  the  orbicularis  palpebrarum  around  the  margin  of  the  orbit  and 
open  the  socket  of  the  eye. 

Scratch  in  the  fascia  at  the  upper  part  until  the  levator  palpebrse  superioris 
is  found.  Also  find  the  pulley  of  the  superior  oblique  at  the  inner,  superior, 
and  anterior  part  of  the  cavity. 

Below  find  the  origin  of  the  inferior  oblique. 

Now  the  pulley  of  the  superior  oblique  and  the  origin  of  the  inferior  oblique 
must  be  divided,  and  then  after  separating  the  orbital  fascia  from  the  bony 
wall  the  arteries,  nerves,  veins,  and  muscles  are  to  be  divided  as  far  posteri- 
orly as  possible,  and  the  eye  removed  for  further  study. 

If  the  brain  has  been  removed  as  previously  directed  and  the  skull  is  not  to 
be  kept,  the  student  should  remove  the  upper  wall  of  the  orbit  as  follows  : — 

With  a  fine  saw  cut  through  the  vertical  plate  of  the  frontal  bone  still  left, 
over  the  outer  and  inner  angles  of  the  orbit.  Break  this  piece  of  bone  off. 
Separate  the  orbital  fascia  from  the  roof  of  the  orbit,  marking  the  location  of 
the  pulley  of  the  superior  oblique,  as  far  posterior  as  the  sphenoidal  fissure. 
With  a  pair  of  bone  cutters  or  a  chisel  cut  the  roof  of  the  orbit  away,  leaving 
the  pulley  of  the  superior  oblique  in  place. 

Remove  the  presenting  portion  of  the  orbital  fascia,  and  carefully  pick  away 
the  fat  which  covers  the  several  structures  pertaining  to  the  eye. 


THE  HEAD,  ANTERIOR.  49 

The  Orbital  Fascia,  or  Periosteum. 

This  lines  the  interior  of  the  bones  composing  the  orbit, 
is  continuous  with  the  dura  through  the  optic  foramen  and 
the  sphenoidal  fissure,  forms  the  capsule  of  the  lachrymal 
gland,  the  lining  for  the  lachrymal  canal,  and  the  pulley 
for  the  superior  oblique  muscle,  at  the  anterior  margin  of 
the  orbit  becomes  continuous  with  the  periosteum  covering; 
the  exterior  of  the  bones,  and  also  sends  to  the  eye-lids  a 
fibrous  expansion — the  palpebral  fascia. 

The  Muscular  Fasciae. 

This  consists  of  the  connective  tissue  envelopes  for  the 
muscles  and  the  eye-ball  anterior  to  the  insertion  of  the  recti 
and  oblique  muscles,  from  where  it  is  reflected  on  to  the  eye- 
lids and  orbital  margin.  This  layer  also  forms  the  cover- 
ing for  the  nerves  and  vessels. 

Tenon's  Capsule. 

This  is  the  connective  sheath  for  the  optic  nerve  and  the 
posterior  two-thirds  of  the  eye-ball.  Anteriorly  it  passes 
into  the  fascia;  for  the  muscles,  the  sclerotic  coat,  and  ocular 
conjunctiva  of  the  eye  ;  posteriorly  it  blends  with  the  orbital 
fascia. 

The  Frontal  Nerve.     Diag.  4.      Fig.  11. 

This  enters  the  orbit  just  external  to  the  fourth  nerve, 
crosses  the  levator  palpebrae,  and  at  the  middle  of  the 
orbit  divides  into  the  supra-orbital  and  supratrochlear 
nerves. 

The  former  leaves  the  orbit  through  the  supra-orbital 
foramen  or  notch,  and  the  latter,  after  passing  above  the 
pulley  of  the  superior  oblique,  leaves  at  the  inner  angle  of 
the  orbit.  For  the  termination  distribution  of  these  nerves 
see  page  25. 
4 


50  A  MANUAL   OF  ANATOMY. 

The  Lachrymal  Gland,  Nerve,  and  Artery.      Fig.  1 1 . 

The  lachrymal  gland  is  a  small  gland  lying  at  the  ante- 
rior, outer,  and  upper  part  of  the  socket  of  the  eye.  Its 
capsule  is  formed  by  an  extension  from  the  orbital  fascia 
(see  above),  by  which  the  gland  is  retained  in  place. 

The  several  small  ducts  open  at  the  outer,  upper  part 
of  the  conjunctiva  of  the  eye. 

The  lachrymal  nerve  enters  the  orbit  through  the  external 
angle  of  the  sphenoidal  fissure.  It  is  accompanied  by  the 
lachrymal  artery  from  the  ophthalmic,  and  both  run  along 
the  upper  border  of  the  external  rectus  muscle  to  the  lach- 
rymal gland. 

Levator  Palpebree  Superioris. 

Origin. — Above  and  in  front  of  the  optic  foramen. 
Insertion. — Into  the  tarsus  of  the  upper  eye-lid. 
Nerve  Supply.- — Third  cranial  nerve. 
Action. — To  raise  the  upper  eye-lid. 

Superior  Oblique. 

Origin. — In  front  of  the  inner  margin  of  the  optic  foramen. 

Insertio7i. — Into  the  outer  surface  of  the  eye-ball. 

Nerve  Supply. — The  fourth  cranial  nerve. 

Action. — Alone,  to  move  the  eye  downward  and  outward. 

The  pulley  for  the  superior  oblique  is  a  ring  of  fibrous 
tissue  attached  to  the  anterior,  inner,  and  superior  portion 
of  the  orbit  cavity  through  which  passes  the  tendon  of  the 
superior  oblique  muscle. 

The  Fourth  Cranial  Nerve.     Fig.  1 1 .      Diags.  3  and  4. 

This  comes  through  the  sphenoidal  fissure,  lying  at  the 
inner  and  superior  angle,  and  proceeds  to  the  superior 
oblique,  which  it  supplies.  In  its  course  it  crosses  above 
the  origin  of  the  levator  palpebrae. 


{From  a  preparation  in  the  Museujn  of  the  University  Medical  College.) 
Fig.  12.  — I,  Nasal  branch  of  the  anterior  ethmoidal  artery  and  vein.  2,  Naso-palatine 
(septal)  branch  of  the  internal  maxillary  artery  and  vein.  3,  Optic  nerve.  4,  Internal 
carotid  artery.  5,  Third  nerve.  6,  Sixth  nerve.  7,  Fourth  nerve.  8,  Fifth  nerve.  9,  Sev- 
enth nerve.  10,  Eighth  nerve.  11,  Vertical  plate  of  ethmoid  bone.  12,  Sphenoidal  sinus. 
13,  Vomer.  14,  Internal  pterygoid  muscle.  15,  Glosso-pharyngeal  nerve.  16,  Spinal 
portion  of  spinal  accessory  nerve.  The  nerve  is  seen  passing  up  to  the  jugular  foramen, 
into  which  are  also  passing  the  glosso-pharyngeal  and  pneumogastric  nerves.  17,  Ex- 
ternal portion  of  spinal  accessory.  18,  Cervical  sympathetic  and  ganglion.  19,  Pneumo- 
gastric nerve.     20,  Internal  carotid  artery.     21,  Gustatory  nerve.     22,  Mylo-'-yoid  nerve. 


52  A  MANUAL   OF  ANATOMY. 

DISSECTION. 
Divide  the  levator  palpebree,  superior  oblique  muscles,  and  frontal  nerve. 

Superior  Rectus. 

Origin. — From  the  upper  margin  of  the  optic  foramen. 

Insertion. — Into  the  upper  surface  of  the  sclerotic  coat 
just  behind  the  cornea. 

Nerve  Supply. — The  third  cranial  nerve. 

Action. — To  draw  the  cornea  upward,  also  draw  the 
cornea  inward  and  slightly  rotate  it. 

DISSECTION. 
Remove  the  lachrymal  gland,  with  its  nerve  and  artery,  and  turn  them  out- 
ward. Divide  the  superior  rectus.  Clean  the  external  and  internal  recti, 
the  ophthalmic  artery,  vein,  nasal  nerve,  and  their  branches.  Be  very  careful 
to  dissect  out  the  ophthalmic  ganglion  which  lies  upon  the  outer  and  upper 
part  of  the  optic  nerve.  Save  the  roots  which  pass  to  the  ganglion  and  the 
ciliary  nerves  which  pass  forward  to  the  eye.  Clean  the  optic  nerve  from  the 
foramen  to  the  eye-ball. 

External  and  Internal  Recti. 

The  External. 

Origin. — By  two  heads.  The  upper  one  from  the  outer 
margin  of  the  optic  foramen,  the  lower  one  from  the  lower 
margin  of  the  sphenoidal  fissure  and  the  ligament  of  Zinn. 

The  Ligament  of  Zinn  is  a  tendon  attached  around  the 
margin  of  the  optic  foramen,  except  at  its  upper  and  outer 
part,  and  gives  origin  to  the  external,  inferior,  and  internal 
recti. 

Between  the  two  heads  of  the  external  rectus  pass  the 
third,  nasal  branch  of  the  fifth,  the  sixth  cranial  nerves, 
and  the  ophthalmic  vein. 

The  Internal. 

Origin. — From  the  inner  side  of  the  optic  foramen. 


THE  HEAD,  ANTERIOR.  53 

Insertion. — The  two  recti  are  inserted  into  the  sclerotic 
of  the  eye-ball  about  a  fourth  of  an  inch  behind  the  corneo- 
sclerotic  junction. 

Nerve  Supply. — The  external  rectus  by  the  sixth  cranial 
nerve,  the  other  by  the  third. 

Action. — The  external  and  internal  recti  muscles  move 
the  eye-ball  outward  or  inward  without  any  rotation. 

The  Ophthalmic  Artery  and  Branches. 

The  ophthalmic  is  a  large  branch  from  the  front  of  the 
internal  carotid  as  it  is  turning  upward  to  the  brain  through 
the  cavernous  sinus. 

The  artery  enters  the  orbit  through  the  optic  foramen, 
with  the  optic  nerve  lying  external  and  inferior  to  the 
nerve. 

The  artery  runs  forward  in  a  tortuous  course  above  the 
optic  nerve  and  along  the  inner  side  of  the  orbit  to  the 
front  of  the  same,  where  it  divides  into  the  nasal  and  frontal 
branches. 

Its  branches  are  the  lachrymal,  to  the  lachrymal  gland  ; 
the  supra-orbital,  which  accompanies  the  nerve  of  the  same 
name  through  the  supra-orbital  notch  or  foramen  to  the 
front  of  the  forehead  (see  page  26)  ;  the  central  artery  of 
the  retina,  which  penetrates  the  optic  nerve  one-fourth  of 
an  inch  behind  the  eye-ball  and  runs  within  that  nerve  to 
the  retina  ;  the  muscular,  to  the  muscles  of  the  eye  ;  the 
ciliary  arteries,  grouped  in  three  sets,  the  short  posterior 
(five  or  six),  the  long  posterior  (two),  and  the  anterior 
ciliary,  from  the  surrounding  muscular  branches  and  lach- 
rymal artery  ;  all  these  pass  to  the  eye,  the  posterior  to  its 
fundus  and  the  anterior  along  the  tendons  of  the  muscles 
to  the  middle  zone  of  the  eye  ;  the  posterior  ethmoidal, 
which    leaves  the    orbit    through  the   posterior  ethmoidal 


54  A  MANUAL   OF  ANA  TOMY. 

foramen  and  breaks  up  into  branches  to  the  ethmoidal  cells, 
the  dura,  and  the  interior  of  the  nose  ;  the  anterior  eth- 
moidal artery  takes  an  identical  course  with  the  nasal  nerve 
through  the  anterior  ethmoidal  foramen,  cranial  cavity,  and 
nasal  slit  into  the  nasal  cavity ;  its  branches  are  ethmoidal, 
meningeal,  nasal,  and  some  small  cutaneous  twigs  ;  the 
palpebral  arteries,  to  supply  the  upper  and  lower  eye-lids  ; 
lastly,  the  terminal  branches,  or  the  frontal  and  nasal.  The 
frontal  turns  upward  at  the  inner  margin  of  the  supra- 
orbital arch  to  supply  the  front  of  the  forehead  between  the 
median  line  and  the  supra-orbital  artery.  (See  page  26.) 
The  supratrochlear  nerve  and  frontal  artery  run  together. 
The  nasal  artery  runs  downward  along  the  inner  part  of 
the  eye  to  the  side  of  the  nose,  where  it  anastomoses  with 
the  angular  branch  of  the  facial.  It  gives  off  a  small  trans- 
verse branch  which,  with  a  similar  one  from  the  other  side, 
forms  an  arch  over  the  front  of  the  base  of  the  nose. 

The  Ophthalmic  Veins. 

The  superior  is  formed  at  the  front  of  the  orbit  by  the 
junction  of  the  veins  which  accompany  the  frontal  and  supra- 
orbital arteries.  It  passes  backward  above  the  optic  nerve 
along  with  the  ophthalmic  artery  to  the  sphenoidal  fissure, 
through  which  it  passes  to  empty  into  the  cavernous  sinus. 

The  inferior  vein  begins  at  the  front  of  the  orbit  also, 
takes  a  course  backward  below  the  optic  nerve,  and  at  the 
back  of  the  orbit  empties  into  the  superior  ophthalmic  vein 
or  separately  into  the  cavernous  sinus.  The  inferior  com- 
municates with  the  pterygoid  plexus  through  the  spheno- 
maxillary fissure. 

The  Ophthalmic  Nerve.      Fig.  1 1 .      Diags.  3  and  4. 

This  is  the  first  or  superior  division  of  the  fifth  cranial 
nerve.     It  is  a  sensory  nerve  solely.      It  enters  the  orbital 


{From  a  preparation  in  the  Museum  of  the  University  Medical  College.) 
Pig.  13.  The  Vertical  Plate  of  the  Ethmoid  and  the  Vomer  Turned  Back 
so  AS  to  Show  the  Nasal  Cavities  and  their  Nerve  Supply.— i,  Olfactory  bulb, 
nerves  and  tract.  2,  Opening  of  sphenoidal  sinus  (No.  3)  into  the  superior  meatus. 
4  Superior  turbinated  bone.  5,  Superior  meatus.  6,  Middle  turbinated  bone.  7,  Middle 
meatus.  Shows  the  opening  into  the  antrum  of  Highmore.  8,  Inferior  turbinated  bone. 
9,  Inferior  meatus.  10,  Naso-palatine  (septal)  branch  of  Meckel's  ganglion.  11,  Nasal 
nerve. 


56  A  MANUAL  OF  AAA  TO  MY. 

cavity  through  the  sphenoidal  fissure  in  three  divisions,  the 
frontal,  lachrymal,  and  the  nasal. 

The  frontal  and  lachrymal  nerves  enter  above  the  rectus 
externus,  the  nasal  between  the  two  heads  of  that  muscle. 

The  frontal  and  lachrymal  branches  have  already  been 
given  above.     (Pages  49  and  50.) 

The  Nasal  Nerve.      Fig.  13.      Diag.  4. 

This  nerve  runs  forward  and  inward  between  the  rectus 
superior  and  the  optic  nerve  to  the  inner  wall  of  the  orbit, 
where  it  enters  the  anterior  ethmoidal  foramen,  passes 
through  it  into  the  cranial  cavity,  runs  forward  on  the  outer 
border  of  the  cribriform  plate  of  the  ethmoid  bone,  leaves 
the  cranium  by  traversing  the  nasal  slit  at  the  side  of  the 
crista  galli,  and  appears  in  the  nasal  fossa,  where  it  termi- 
nates in  three  branches. 

In  the  orbit  the  nerve  gives  off  the  following  branches  : — 

Between  the  two  heads  of  the  rectus  externus,  the  long- 
root  to  the  ophthalmic  ganglion.  A  very  slender  filament 
about  half  an  inch  long. 

Two  long-  ciliary  filaments  to  the  eye.  These  run  along 
the  inner  side  of  the  optic  nerve. 

The  infra  trochlear  nerve  is  the  last  branch  given  off 
just  before  the  nerve  leaves  the  orbit.  It  passes  forward 
beneath  the  pulley  for  the  superior  oblique  and  supplies  the 
integument  about  the  inner  part  of  the  eye  and  upper  part 
of  the  nose,  also  the  mucous  membrane  of  the  inner  part  of 
the  eye,  lachrymal  sac,  and  caruncle. 

The  remaining  branches  will  be  given  when  describing 
the  nasal  fossae. 

The  Ophthalmic,  or  Lenticular  Ganglion.      Fig.  ii. 

This  is  a  ganglion  developed  in  connection  with  the  oph- 
thalmic division  of  the  fifth  nerve.     It  is  about  as  large  as 


THE  HEAD,  ANTERIOR.  57 

the  head  of  a  small  pin.  Is  situated  at  the  outer  and  upper 
part  of  the  optic  nerve  at  about  its  middle,  between  the  nerve 
and  the  external  rectus  and  one-fourth  of  an  inch  in  front 
of  the  sphenoidal  fissure. 

The  ganglion  receives  its  sensory  root  from  the  nasal 
nerve  (the  long  root),  the  motor  root,  from  the  third  cranial 
nerve  (the  short  root),  and  its  sympathetic  root  from  the 
plexus  on  the  carotid  artery  within  the  cavernous  sinus. 

Eight  or  ten  minute  filaments  pass  forward  from  the  gan- 
glion— the  short  ciliary  nerv^es — to  supply  the  eye -ball. 

The  Optic  Nerve.      Figs.   lo,  ii,  12. 

The  optic  nerve  enters  the  orbit  through  the  optic  fora- 
men with  the  ophthalmic  artery,  as  already  described,  lying 
above  and  to  the  inside  of  the  artery.  It  passes  forward  to 
enter  the  back  of  the  eye-ball. 

The  optic  nerve  is  the  central  structure  passing  to  the 
eye.  It  is  surrounded  by  the  ocular  nerves,  arteries,  veins, 
and  muscles,  and  a  packing  of  adipose  tissue  between  them 
all  to  hold  them  in  their  proper  places. 

The  Sixth  Cranial  Nerve.      Figs.  10,    ii,  12. 

It  comes  into  the  orbital  cavity  through  the  sphenoidal 
fissure  and  between  the  two  heads  of  the  external  rectus 
muscle,  to  which  it  is  distributed.      Diags.  3  and  4. 

DISSECTION. 

Complete  the  dissection  of  the  eye  cavity  by  dividing  the  internal  and  ex- 
ternal oblique  muscles  and  raising  the  eye-ball  first  to  one  side  and  then  to 
the  other. 

The  Third  Cranial  Nerve.      Figs.   10,  11,  12.       Diags.  3 
and  4. 
The  motor  ocuU  enters  the  orbit  through  the  inner  part 
of  the  sphenoidal  fissure  in  the   shape   of  two   branches, 


58  A  MANUAL   OF  ANATOMY. 

which  are  separated  by  the  nasal  nerve.  These  branches 
run  forward  between  the  two  heads  of  the  external  rectus. 
The  superior  division  of  the  third  nerve.  This  is  the 
smallest ;  it  passes  forward  and  inward  over  the  optic  nerve 
to  the  rectus  superior  and  levator  palpebrse  superioris.  The 
lower  division  is  the  larger  and  divides  into  three  branches, 
one  to  the  rectus  internus,  another  to  the  rectus  inferior, 
the  third  to  the  obliquus  inferior.  From  this  last  branch 
the  motor  root  of  the  ophthalmic  ganghon  arises. 

Rectus  Inferior. 

Origin. — From  the  lower  margin  of  the  optic  foramen. 

Insertion. — Into  the  lower  part  of  the  sclerotic  coat  of  the 
eye  just  behind  the  corneal  margin. 

Nerve  Supply. — The  inferior  branch  of  the  third  nerve. 

Action. — To  depress  and  at  the  same  time  slightly  rotate 
and  draw  the  cornea  inward. 

Obliquus  Inferior. 

Origin. — From  the  front  of  the  orbital  cavity  at  the  junc- 
tion of  its  lower  and  inner  surfaces,  just  outside  the  opening 
of  the  nasal  duct. 

Insertion. — Into  the  outer  posterior  part  of  the  eye-ball 
under  the  external  rectus. 

Nerve  Supply. — The  third  or  motor-oculi  through  the  in- 
ferior branch. 

Action. — To  rotate  the  cornea  outward,  and  to  turn  the 
eye-ball  slightly  upward  and  outward. 

DISSECTION. 

If  the  skull  has  been  opened,  the  brain  removed,  the  interior  of  the  base  of 
the  skull  dissected,  and  the  orbit  finished,  then  take  up  the  dissection  of  the 
face. 

Nothing  upon  the  face  has  been  dissected  except  the  orbicularis  palpebra- 
rum. The  structures  are  covered  by  a  layer  of  fascia  and  the  upward  projec- 
tion of  the  platysma. 


THE  HEAD,  AXTERIOR.  59 

The  fascice  and  platysma  and  its  facial  portion,  the  risorius,  are  all  to  be 
studied  and  then  removed,  and  the  facial  muscles  above  then  below  the  mouth 
are  to  be  cleaned.  Along  with  the  dissection  of  the  muscles  will  proceed  the 
cleaning  of  the  nerves,  veins  (facial  especially),  and  the  arteries. 

Risorius. 

This  is  a  thin  sheet  of  loosely  joined  muscular  fibres,  an 
extension  and  derivation  of  the  plat>'sma,  which  extends  from 
the  masseteric  and  parotid  fasciae  to  the  angle  of  the  mouth. 
The  Masseteric  and  Parotid  Fasciae. 

The  upward  continuation  of  the  superficial  layer  of  the 
deep  cervical  fascia  from  the  neck  over  the  masseter  muscle 
and  parotid  gland  is  called  the  masseteric  and  parotid  fascia 
respectively.      See  page  138. 

The  former  is  attached,  above,  to  the  lower  border  of  the 
zygomatic  arch,  and  below,  to  the  lower  and  posterior  bor- 
ders of  the  lower  jaw.  An  extension  of  this  fascia  from  the 
angle  of  the  jaw  to  the  styloid  process  is  called  the  stylo- 
maxillary  ligament.  It  serves  to  separate  the  parotid  from 
the  submaxillary  gland. 

The  latter  (parotid)  fascia  covers  in  the  parotid  gland.  In 
front  it  is  continuous  with  the  masseteric  fascia  ;  above, 
attached  to  the  zygomatic  arch  ;  behind,  to  the  front  of  the 
mastoid  process,  and  below%  extends  into  the  cervical  fascia. 

Zygomaticus  Major.      Fig.  3. 

Origin. — From  the  outer  surface  of  the  malar  bone. 

Insertion. — Into  the  orbicularis  oris,  levator  anguli  oris, 
and  skin  at  the  angle  of  the  mouth. 

Nerve  Supply. — The  seventh  or  facial  by  its  infra-orbital 
branch. 

Action. — To  raise  and  retract  the  angle  of  the  mouth. 
Zygomaticus  Minor. 

Origin. — The  lower  part  of  the  anterior  surface  of  the 
malar  bone. 


60  ■  A  MANUAL  OF  ANATOMY. 

Insertion. — Into  the  outer  margin  of  the  levator  labii  su- 
perioris. 

Nerve  Supply. — Same  as  above. 

Action. — To  raise  the  outer  part  of  the  upper  lip. 
Levator  Labii  Superioris. 

Origin. — From  the  superior  maxillary  bone  just  below 
the  orbit. 

hisertion. — Into  the  orbicularis  oris  and  skin  of  the 
upper  lip. 

Nerve  Supply. — Infra-orbital  branch  of  the  facial. 

Action. — To  elevate  the  upper  lip. 

Levator  Labii  Superioris  Alsequae  Nasi. 

Origin. — From  the  nasal  process  of  the  superior  maxilla. 

Insertion. — An  internal  fasciculus  into  the  wing  of  the 
nose,  and  by  the  outer  portion  into  the  orbicularis  oris  and 
the  skin  of  the  upper  lip. 

Nerve  Supply. — The  infra-orbital  branch  of  the  facial. 

Action. — To  raise  the  wing  of  the  nose  and  the  upper 
lip. 
Levator  Ang-uli  Oris.      Fig.  3. 

Origin. — From  the  canine  fossa  of  the  superior  maxil- 
lary bone,  below  the  infra-orbital  foramen. 

Insertion. — Into  the  orbicularis  oris  at  the  angle  of  the 
mouth. 

Nerve  Supply. — The  facial  by  the  infra-orbital  branch. 

Action. — To  raise  the  angle  of  the  mouth. 

DISSECTION. 
The  parotid  gland  and  masseter  muscle  are  covered  by  a  dense  layer  of 
fascia,  the  parotid  and  masseteric,  a  prolongation  of  the  superficial  layer  of 
the  cervical  fascia  upward  to  the  zygomatic  arch.  Be  very  careful  in  remov- 
ing this  fascia  to  leave  the  branches  of  the  facial  nerve,  the  auriculo-temporal 
nerve,  the  transverse  facial  artery,  Stenson's  duct,  and  the  detached  portion  of 
the  parotid  gland  (glandula  socia  parotidis)  uninjured  upon  the  masseter  muscle. 


THE  HEAD,  ANTERIOR.  61 

The  branches  of  the  temporofacial  division  of  the  facial  nerve  are  the 
temporal,  malar,  and  infra-orbital.     For  these  see  below. 

Two  branches  of  the  cervicofacial  division  are  found  upon  the  face  ;  these 
are  the  buccal  and  the  supraviaxillary.  These  structures  are  to  be  care- 
fully dissected  out. 

To  find  the  branches  of  the  facial  nerve  look  for  them  in  the  region 
indicated  by  their  names  ;  it  is  usually  best  to  begin  with  the  infra-orbital,  and 
after  one  has  been  found  to  trace  it  forward  to  its  distribution  and  backward 
to  its  source.  In  tracing  any  nerve  of  the  facial  backward  other  branches 
will  be  found  and  the  dissection  carried  on  step  by  step  until  all  the  branches 
are  cleaned. 

The  Facial  Nerve.      Figs.  2,  3,  10,  ii,  and  14. 

This  leaves  the  skull  by  the  stylomastoid  foramen,  gives 
off  small  branches  (posterior  auricular,  nerve  to  the  pos- 
terior belly  of  the  digastric,  and  the  nerve  to  the  stylo- 
hyoid muscle),  then  divides  into  the  temporofacial  and 
the  cervicofacial  trunks. 

The  temporofacial  gives  off  the  temporal  which  passes 
upward  through  the  parotid  in  front  of  the  temporal  artery, 
where  it  divides  into  several  branches,  to  the  temporal 
region  ;  it  communicates  with  the  auriculo-temporal  nerve 
behind  the  temporal  artery  ;  the  malar  branch  runs  upward 
and  forward  over  the  malar  bone  ;  the  i)ifra-orbital  branch 
extends  forward  between  the  zygoma  and  Stenson's  duct, 
then  under  the  zygomaticus  major  and  minor  to  supply  the 
superior  labial  muscles  and  enter  into  a  plexus  with  the 
infra-orbital  of  the  fifth.      See  page  151. 

The  cervicofacial  division  gives  off  the  buccal  to  the 
buccinator  (the  real  motor  supply) ;  the  sjipraviaxillary 
above,  and  the  iiiframaxillary  below  the  lower  jaw,  the 
former  supplying  the  inferior  labial  muscles  and  communi- 
cating with  the  mental  nerve,  the  latter  suppl)'ing  the 
platysma  and  joining  with  the  superficial  cervical  nerve. 

Besides  these  communications  mentioned  the  branches 
of  both  divisions  communicate  with  the  branch  above  and 


62  A  MANUAL   OF  ANATOMY. 

below  itself,  thus  forming  a  plexus   over  the  entire   side  of 
the   face. 

All  these  branches  in  the  parotid  gland  lie  anterior  or 
superficial  to  the  external  carotid  artery  and  the  temporo- 
maxillary  vein. 

The  Temporal  Artery.       Figs.  2,  3. 

Branches  of  the  trunk  of  the  temporal  artery.  The  ante- 
rior auricular  passes  to  the  top  and  front  of  the  ear ;  the 
orbital  is  a  small  branch  which  runs  forward  to  the  orbit 
between  the  two  layers  of  the  temporal  fascia  (see  page  30)  ; 
the  middle  temporal  perforates  the  temporal  fascia  and 
muscle,  just  above  the  zygomatic  arch,  to  reach  the  under 
surface  of  the  temporal  muscle  and  ramify  in  the  fossa 
there  ;  and  the  transverse  facial,  which  is  seen  to  run 
forward  from  the  parotid  gland,  just  below  the  zygomatic 
arch,  between  the  arch  and  Stenson's  duct,  to  anastomose 
with  the  infra-orbital  branch  of  the  internal  maxillary  in 
front,  and  the  muscular  branches  of  the  facial  below  ;  be- 
sides these  there  are  small  twigs  given  to  the  parotid  gland 
and  temporomaxillary  articulation. 

The  Facial  Vein.      Figs.  3,  15. 

This  starts  at  the  inner  angle  of  the  eye  as  the  continua- 
tion of  the  angular  vein.  It  takes  a  direct  course  down- 
ward and  outward  under  the  greater  and  lesser  zygomatic 
muscles  and  platysma  to  the  facial  notch  in  the  lower  jaw, 
where  it  lies  posterior  to  the  artery.  In  its  course  it  re- 
ceives branches  corresponding  to  the  branches  of  the  facial 
artery,  and  communicates  with  the  infra-orbital  vein.  For 
continuation  in  neck,  see  page  74. 

Depressor  Angnli  Oris. 

Origin. — From  the  external  oblique  line  of  the  inferior 
maxillary  bone. 


THE  HEAD,  ANTERIOR.  63 

Insertion. — Into  the  angle  of  the  mouth,  blending  with 
the  other  muscles  at  that  point. 

Nerve  Supply. — The  facial  through  its  supramaxillary 
branch. 

Action. — To  depress  and  retract  the  angle  of  the  mouth. 

Depressor  Labii  Inferioris. 

Origin. — From  the  upper  border  of  the  external  oblique 
line  of  the  inferior  maxilla,  from  near  the  symphysis  to 
beyond  the  mental  foramen. 

Insertion. — Into  the  orbicularis  oris  and  the  skin  of  the 
lower  lip. 

Nerve  Supply. — The  supramaxillary  branch  of  the  facial. 

Action. — To  depress  the   lower  lip. 

Levator  Labii  Inferioris. 

Origin. — From  the  incisi\'e  fossa  of  the  lower  jaw. 

Insertion. — Into  the  skin  of  the  chin. 
■     Nerve  Supply. — The  supramaxillary  branch  of  the  facial. 

Action. — To  raise  the  skin  over  the  point  of  the  chin  and 
protrude  the  lower  lip. 

Orbicularis  Oris.      Fig.  3. 

This  is  the  sphincter  muscle  of  the  mouth,  and  is  ar- 
ranged in  two  portions,  an  internal  or  labial,  and  an  exter- 
nal or  facial. 

The  labial  portion  has  no  bony  attachments.  The  facial 
is  attached  by  slender  slips  to  the  septum  of  the  nose,  and 
the  incisive  fossae  of  the  superior  and  inferior  maxillary 
bones,  besides  blending  with  the  muscles  passing  to  the 
mouth. 

Nerve  Supply. — The  facial  through  its  buccal  and  supra- 
maxillary branches. 

Action. — To  close  the   lips,  vertically  and  transversely  ; 


64  A  MANUAL  OF  ANA  TOMY. 

the  facial  portion  will  pout  the   lips,  the   labial  will  press 
them  against  the  teeth. 

The  Facial  Artery.      Figs.  2,  3,  14. 

On  the  face.  The  facial  artery  comes  into  the  face  from 
the  neck  over  the  lower  border  of  the  inferior  maxillary- 
bone,  lying  in  the  facial  notch  just  at  the  junction  of  the 
ramus  and  body,  at  the  anterior  border  of  the  masseter 
muscle. 

It  takes  a  very  tortuous  course  around  the  angle  of  the 
mouth  and  along  the  side  of  the  nose  to  terminate  at  the 
inner  angle  of  the  eye. 

In  its  course  it  passes  under  the  platysma,  zygomatic 
major  and  minor,  the  levator  labii  superioris,  and  levator 
labii  superioris  alsequse  nasi. 

The  facial  vein  lies  behind  the  artery. 

Branches  of  the  Facial  Artery.      On  the  Face. 

(i)  Muscular,  to  the  masseter  and  buccinator  muscles. 
The  masseteric  branches  anastomose  with  the  transverse 
facial  and  muscular  branches  from  the  internal  maxillary. 
The  buccal,  with  the  same,  and  also  with  the  infra-orbital, 
from  the  internal  maxillary.  (2)  The  inferior  labial.  Its 
course  is  forward  under  the  depressor  anguli  oris  and  mid- 
way between  the  border  of  the  lip  and  the  chin,  to  supply 
the  muscles  of  the  lower  lip.  It  anastomoses  with  the 
facial  branches  above  and  below  itself  and  across  the  median 
line. 

All  the  anterior  facial  branches  anastomose  across  the 
median  line  with  corresponding  arteries  from  the  opposite 
facial,  as  well  as  with  the  arteries  next  above  and  below. 
Exception  :  the  coronary  arteries  do  not  anastomose  with 
each  other,  except  at  the  angle  of  the  mouth.  (3)  The 
inferior  coronary.    Extends  forward  beneath  the  depressor 


THE  HEAD,  ANTERIOR.  65 

anguli  oris  to  the  lower  lip,  and  runs  inward  between  the 
mucous  membrane  and  the  orbicularis  oris.  It  anasto- 
moses with  the  opposite  coronary  artery  and  the  arteries 
below.  (4)  The  superior  coronary.  Takes  a  similar  course 
along  the  upper  lip.  It  supplies  the  upper  lip  and  gives  off 
the  artery  of  the  septum  of  the  nose,  (5)  The  lateral  nasal 
arter}^  This  is  a  small  (sometimes  a  large)  branch  to  the 
side  of  the  nose.  It  anastomoses  with  the  nasal  from  the 
ophthalmic,  and  with  the  facial  branches  adjacent.  (6)  The 
angular  artery.  The  last  portion  of  the  facial  along  the 
side  of  the  nose.  It  terminates  at  the  inner  angle  of  the 
eye  by  anastomosing  with  the  nasal  branch  of  the  ophthal- 
mic. 

The  facial  anastomoses  on  the  face. 

As  already  stated,  the  facial  branches  toward  the  middle 
line  freely  communicate  with  each  other.  They  also  anas- 
tomose with  the  artery  next  above  and  below  (excepting 
the  coronary  arteries  do  not  anastomose  with  each  other). 
The  other  connections  are,  with  the  temporal,  by  the  mas- 
seteric and  buccal  branches  uniting  with  the  transverse 
facial ;  with  the  internal  maxillary,  through  the  inferior 
labial  and  coronary  joining  with  the  mental  (of  the  inferior 
dental),  by  the  muscular  branches  to  the  masseter  and  buc- 
cinator from  both  arteries,  and  through  the  infra-orbital  ; 
and  with  the  ophthalmic  by  its  nasal  branch  anastomosing 
with  the  artery  of  the  septum,  the  lateral  nasal,  and  angular 
branches  of  the  facial. 


DISSECTION. 
Cut  the  parotid  gland  away  piecemeal,  finish  the  facial  nerve  ;  the  upper 
portion  of  the  external  carotid  artery  and  its  terminal  branches,  the  temporal 
and  internal  maxillary  arteries ;  the  transverse  facial  artery  and  posterior  auri- 
cular arteries ;  and  the  temporomaxillary  vein  or  sinus. 
5 


66  A  MANUAL  OF  ANATOMY. 

The  Parotid  Gland.     Figs.  3,  14. 

This  is  a  large  salivary  gland,  which  fills  up  the  space 
below  the  zygoma,  and  between  the  ramus  of  the  lower 
jaw  and  the  auditory  and  mastoid  processes,  and  extends 
downward  as  low  as  the  level  of  the  angle  of  the  jaw. 

Its  lobes  extend  forward  (pterygoid),  upward  (glenoid), 
and  inward  (carotid),  between  the  surrounding  structures. 
One  portion  usually  detached  and  lying  upon  the  masseter 
muscle  is  the  socia  parotidis,  which  connects  with  the  paro- 
tid duct  by  a  separate  opening. 

The  duct  of  the  parotid  gland  is  Stenson's.  It  passes 
forward  across  the  masseter  half  an  inch  below  the  zygoma, 
pierces  the  buccinator  muscle,  and  opens  into  the  mouth 
opposite  the  second  upper  molar  tooth.     Figs.  2,  3,  4. 

The  gland  is  covered  by  the  extension  upward  of  the 
cervical  fascia  called  the  parotid  fascia.     See  page  59. 

It  is  separated  from  the  submaxillary  gland  by  the  stylo- 
maxillary  ligament.     Page  59. 

Within  the  parotid  are  found  the  facial  nerve  and  its 
primary  divisions  and  branches  (forming  the  pes  anserinus)  ; 
the  termination  of  the  external  carotid  artery,  its  posterior 
auricular  branch,  the  beginning  of  the  internal  maxillary 
and  the  temporal  arteries  ;  the  transverse  facial  from  the 
temporal,  as  also  the  glandular  branches  from  these  arteries 
to  the  parotid  itself;  and  the  temporomaxillary  vein. 

The  arterial  supply  is  from  the  arteries  within  the 
gland,  the  nerve  supply  from  the  seventh,  great  auricular, 
auriculotemporal,  and  sympathetic  plexus  on  the  carotid 
artery. 

The  veins  open  into  the  temporomaxillary  sinus. 

The  lymphatics  empty  into  the  superficial  and  deep 
lymphatic  glands  of  the  neck. 


THE  HEAD,  ANTERIOR.  67 

Masseter.     Figs.  2,  3,  4. 

Origin. — The  deep  portion,  from  the  inner  surface  of  the 
zygomatic  arch  and  from  the  posterior  third  of  the  lower 
border  of  the  same  ;  the  superficial  portion,  from  the  lower 
border  of  the  anterior  two-thirds  of  the  zygomatic  arch 
and  malar  bone. 

Insertion. — The  deep  portion,  into  the  upper  half  of  the 
ramus  of  the  lower  jaw  and  coronoid  process  ;  the  super- 
ficial portion,  into  the  lower  half  of  the  ramus  extending 
as  far  as  the  angle. 

Nerve  Supply. — The  inferior  maxillary  branch  of  the 
fifth  cranial  nerve  through  its  masseteric  branch. 

Action. — To  close  the  jaw  ;  and,  by  the  superficial  por- 
tion, to  slightly  protract  it. 

Buccinator,     Figs.  3,  4. 

Origin. — From  the  pterygomaxillary  ligament  (a  liga- 
ment extending  from  the  hamular  process  of  the  internal 
plate  of  the  pterygoid  bone  to  the  posterior  extremity  of 
the  mylohyoid  ridge  of  the  inferior  maxilla)  and  from  the 
outer  surface  of  the  alveolar  process  of  the  superior  and 
inferior  maxillary  bones  opposite  the  molar  teeth. 

Insertion. — Into  the  orbicularis  oris,  some  of  the  lower 
fibres  passing  into  the  upper  lip,  and  some  of  the  upper 
fibres  into  the  lower  lip. 

Nei^oe  Supply. — The  seventh  cranial  nerve  through  its 
buccal  branch.  The  buccal  branch  of  the  inferior  maxil- 
lary nerve  passes  to  the  muscle  also.     See  page  1 17. 

Action. — To  retract  the  angles  of  the  mouth,  to  flatten 
the  cheeks,  and  expel  the  contents  of  the  mouth,  also  to 
force  the  food  between  the  teeth. 


68  A  MANUAL   OF  ANATOMY. 

The  Mental,  Infra-orbital  and  Supra-orbital  Foramina. 

Figs.  3,  4,  II. 

The  mental  foramen  is  in  the  lower  jaw,  in  a  line  with  the 
supra-orbital  and  infra-orbital  foramina.  Through  it  come 
the  mental  nerve  and  artery  (branches  from  the  inferior 
dental  nerve  and  artery,  and  these  arise  in  turn  from  the 
inferior  maxillary  nerve  and  internal  maxillary  artery). 

The  supra-orbital  foramen  transmits  the  artery,  vein,  and 
nerve  of  this  name.  The  artery  is  a  branch  of  the  ophthal- 
mic, the  nerve  of  the  frontal,  which  arises  from  the  ophthal- 
mic. The  vein  empties  into  the  ophthalmic,  an  important 
connection  to  remember. 

The  infra-orbital  foramen  transmits  the  artery,  vein,  and 
nerve  of  the  same  name.  The  artery  is  a  branch  from  the 
internal  maxillary,  the  vein  empties  into  the  internal  max- 
illary vein,  and  the  nerve  is  the  termination  of  the  superior 
maxillary  nerve. 

These  three  foramina  are  in  the  same  line,  and  the  nerves 
which  come  through  them  are  sensory  branches  of  the  three 
trunks  of  the  fifth  cranial  nerve. 


THE  NECK,  Anterior. 

The  Landmarks.     Figs.  14,  15. 

The  region  of  the  neck  is  limited  above  by  the  lower 
jaw,  mastoid  process,  and  a  line  joining  them,  and  the  su- 
perior curved  line  of  the  occipital  bone ;  below,  by  the  top 
of  the  sternum  and  clavicle  ;  laterally,  by  the  linear  ele- 
vation formed  by  the  anterior  borders  of  the  trapezius 
muscles. 

This  area  is  divided  in  front  by  the  median  line  into  two 
symmetrical  portions. 

The  above  boundaries  should  be  identified. 


THE  HEAD,  ANTERIOR.  69 

In  the  median  line  recognize  from  above  downward  the 
(i)  hyoid  bone.  (2)  The  thyroid  cartilage  and  its  forward 
projection,  called  Adam's  apple,  and  the  angle  left  between 
the  alae  of  the  cartilage.  (3)  The  cricoid  cartilage,  just 
below  (and  connected  to  the  thyroid  cartilage  by  a  stout 
membrane  ;  see  page  146)  ;  the  cricoid  cartilage  is  in  front 
of  the  fifth  intervertebral  disc.  (4)  The  trachea,  (5)  ob- 
scured by  the  thyroid  gland,  which  lies  upon  either  side 
of,  and  is  connected  by  its  isthmus  across  the  front  of  the 
trachea.  (6)  Lastly,  the  depression  just  above  the  ster- 
num— fonticulus  gutturis, — and  between  the  anterior  ends 
of  the  clavicles — the  suprasternal,  or  interclavicular  notch. 

Laterally,  from  above  downward,  identify  superior  curved 
line  of  the  occipital  bone  and  the  mastoid  process,  its  base 
and  tip  ;  the  sternomastoid  muscle,  which  forms  a  broad 
elevation,  extending  from  the  mastoid  process  to  the 
sternum  and  inner  end  of  the  clavicle  (when  it  is  put  upon 
the  stretch). 

As  the  arteries  (subclavian,  outer  portion,  and  the 
carotids)  are  injected,  their  position  can  be  recognized  by 
touch,  and  their  course  sketched  upon  the  skin  by  an 
aniline  pencil.  The  superficial  jugular  veins  usually  show 
through  the  integument,  and  their  course  can  be  similarly 
indicated. 

The  position  of  the  sternoclavicular  articulation  should  be 
carefully  noted,  as  it  marks  so  many  important  structures. 

Consult  page  262  for  the  distance  to  which  the  lung 
extends  into  the  base  of  the  neck. 

DISSECTION. 

Incisions. — i.   Carry  the  median  incision  to  the  top  of  the  sternum. 

2.  Make  a  transverse  incision  outward  along  the  clavicle  to  the  point  of 
the  shoulder.  (If  the  upper  e.xtremity  is  being  dissected  this  incision  has 
already  been  made.     See  page  264.) 


70  A  MANUAL   OF  ANA  TOMY. 

3.  Continue  the  incision  from  the  lobe  of  the  ear  along  the  line  of  its  pos- 
terior attachment  to  the  head . 

Reflect  the  integument  from  behind  the  ear,  front,  and  side  of  the  neck,  so 
as  to  expose  the  anterior  border  of  the  trapezius  muscle. 

Platysma  Myoides.     Fig.  14. 

Origin. — From  the  deep  fascia  covering  the  upper  part 
of  the  pectoralis  major,  deltoid,  and  trapezius  muscles,  and 
slightly  from  the  front  of  the  upper  surface  of  the  clavicle. 

Insertion. — Into  the  anterior  three-fourths  of  the  lower 
border  of  the  inferior  maxilla  (the  fibres  of  the  muscle  cross- 
ing the  median  Hne  at  the  point  of  the  chin),  and  into  the 
angle  of  the  mouth. 

Nerve  Supply. — The  superficial  cervical,  from  the  second 
and  third  cervical  nerves,  and  the  inframaxillary  branch  of 
the  cervico-facial  division  of  the  seventh.  The  latter  is  the 
main  supply. 

Action. — To  depress  the  lower  jaw.  This  being  fixed, 
they  will  flex  the  head  and  retract  the  angle  of  the  mouth. 
If  one  acts  it  will  have  the  same  action  on  one  side  of  the 
mouth,  depress  the  jaw ;  if  this  is  resisted,  the  head  will  be 
flexed  laterally  and  the  chin  rotated  to  the  same  side. 

The  upper  part  of  the  muscle  being  the  fixed  part,  it 
raises  the  skin  over  its  origin,  and  in  the  neck  tends  to  draw 
it  away  from  the  deeper  parts. 

DISSECTION. 

After  completing  the  platysma,  begin  at  its  origin  (below)  and  carefully- 
separate  it  from  the  deeper  structures  beneath.  The  nerve  supply  to  the  muscle 
will  be  found,  and,  after  being  recognized,  may  be  divided  and  the  muscle 
rolled  up  on  to  the  lower  part  of  the  face. 

The  first  layer  of  the  cervical  fascia  is  now  exposed ;  the  other  layers  will 
follow  in  order  and  should  be  identified  as  far  as  possible.  In  order  to  do 
this,  consult  the  technical  description  of  the  fascia  as  found  on  page  136. 
Its  description  here  now  would  not  be  so  easily  understood  as  after  the 
dissection  of  the  neck  has  been  completed. 


/ 


^.--^ 


Fie.  14.     Dissection  of  Neck.    ,  .     ,  , 

I    Temporal  arter\ .     Behind  it  is  the  aunculo-temporal  nerve. 

2!  Temporo-faciardivision  of  the  facial  nerve  and  its  three  branches. 

%.  Remains  of  the  parotid  gland.  ,  .      ^.         ,  . 

4]  Cervico-facial  division  of  the  facial  nerve  and  its  three  branches. 

5,  Platysma  myoides. 

6,  Stenson's  duct. 

7,  Masseter  muscle. 

8,  Facial  artery  and  masseteric  branch. 


72 


A  MANUAL  OF  AAATOAfV. 


The  superficial  veins  (jugular)  of  the  neck  are  to  be  dissected,  their  forma- 
tion, course,  and  termination  determined  as  far  as  possible. 

The  superficial  nerves  should  be  fixed  in  mind  by  consulting  Fig.  i6, 
before  the  dissection  of  the  neck  is  attempted,  and  then  traced  out. 

The  Veins  of  the  Neck.     Fig.   15.     Diag.  5. 

The  temporal  and  internal  maxillary  veins  unite  opposite 
the  neck  of  the  lower  jaw  to  form  the  temporomaxillary 
sinus  (or  vein). 


Diag.  5.  The  Veins  of  the  Neck. — i,  Temporal.  2,  Internal  maxillary.  3, 
Temporomaxillary  "  sinus."'  4,  Anterior  division  of  the  temporomaxillary  "sinus." 
5,  Posterior  division  of  the  temporomaxillary  "sinus."  6,  Posterior  auricular.  7, 
External  jugular.  8,  Posterior  external  jugular.  9,  Transverse  cervical.  10,  Supra- 
scapular. II,  Facial.  12,  Communicating  betvi^een  facial  and  anterior  jugular.  13, 
Anterior  jugular.     14,  Internal  jugular.     15,  Subclavian.    16,  Innominate. 


The  temporomaxillary  vein  descends  through  the  sub- 
stance of  the  parotid  gland,  superficial  to  the  external 
carotid,  and  at  the  angle  of  the  jaw  divides  into  an  anterior 
and  a  posterior  trunk. 


Fig.  15.  Dissection  of  Veins  of  Neck. — 1,  Temporo-maxillary  "sinus."  2,  An- 
terior division  of  same.  3,  Posterior  division  of  same.  4,  Posterior  auricular  vein. 
5,  External  jugular.  6,  Superficial  cervical.  7,  Suprascapular.  8,  Connecting  cephalic 
(9)  with  external  jugular.  9.  Cephalic.  10,  Facial.  11,  Internal  jugular.  12,  Commu- 
nicating between  facial  and,  13,  The  anterior  jugular.  14,  Communicating  between  ex- 
ternal and  anterior  jugulars.     15,  Submaxillary  gland. 


74  A  MANUAL  OF  ANA  TOMY. 

The  posterior  branch  is  joined  by  the  posterior  auricular 
vein,  and  the  trunk  thus  formed  is  the  external  jugular 
vein. 

The  external  jugular  descends  vertically,  crosses  the 
sternomastoid  (obliquely),  pierces  the  deep  cervical  fascia 
behind  the  middle  of  the  clavicle,  and  empties  into  the 
subclavian  vein. 

In  its  course  it  receives  from  the  rear  the  posterior  exter- 
nal jugular,  the  superficial  transverse  cervical,  the  supra- 
scapular ;  from  the  front,  a  communicating  vein  from  the 
facial,  internal,  and  (sometimes)  anterior  jugular  veins. 

The  Posterior  External  Jug-ular. — This  vein  drains  the 
blood  from  the  upper  and  back  part  of  the  neck.  It  opens 
into  the  external  jugular  at  the  posterior  margin  of  the 
sternomastoid  muscle. 

The  Anterior  Jugular. — This  is  formed  under  the  chin 
close  to  the  median  line  by  the  union  of  several  small  veins. 
Its  course  is  dowmvard  until  near  the  sternal  end  of  the 
clavicle,  when  it  pierces  the  deep  fascia,  turns  outward 
under  the  sternomastoid,  and  empties  into  the  external 
jugular  close  to  its  termination,  or  into  the  subclavian  vein. 

It  is  connected  by  branches,  varying  in  size,  with  the 
facial,  external,  and  opposite  anterior  jugular  veins. 

The  Facial  Vein  in  the  Neck. — Just  below  the  neck 
this  vein  is  joined  by  the  anterior  division  of  the  temporo- 
maxillary  sinus  ;  it  gives  off  the  anastomotic  vein  to  the 
anterior  jugular,  and  then  empties  into  the  internal  jugular 
at  the  level  of  the  hyoid  bone. 

The  Superficial  Nerves.     Fig.  i6.      Diag.  6. 

These  are  as  follows  : — 

The  inframaxillary  branch  from  the  cervicofacial  divi- 
sion of  the  seventh  ;  which  passes  downward  and  forward 


THE  NECK,  ANTERIOR.  75 

through  the  parotid  gland  (as  already  dissected),  and  then 
courses  forward  below  the  lower  jaw  to  form  under  the 
platysma  a  loose  plexus  with  the  superficial  cervical  nerve. 


Diag.  6.  Diagram  of  the  Cervical  Plexus.  (/.  S.  H.)—I,  First  cervical 
nerve.  //,  Second  cervical  nerve.  ///,  Third  cervical  nerve.  IV,  Fourth  cervical 
nerve.  V\  Fifth  cervical  nerve,  i,  Branch  to  rectus  capitis  lateralis.  2,  Branch  to 
rectus  capitis  anticus  minor.  3,  Lesser  occipital.  4,  Great  auricular.  5,  Superficial 
cervical.  6,  Descendens  hypoglossi.  7,  Communicans  hypoglossi.  S,  Phrenic.  9, 
To  scalenus  medius.  10,  To  levator  anguli  scapulae.  11,  To  trapezius.  12,  Acromial, 
13,  Clavicular,  and  14,  Sternal,  cutaneous  branches.  15,  Cord  joining  first  and  second 
nerves.  16,  Cord  joining  second  and  third  nerves.  17,  Cord  joining  third  and  fiaurth 
nerves.  18,  To  scalenus  medius.  19,  To  levator  anguli  scapulae.  20,  Hypoglossal. 
21,  Branch  to  thyrohyoid.  22,  To  anterior  belly  of  the  omohyoid.  23,  To  sterno- 
hyoid. 24,  To  sternothyroid.  25,  To  posterior  belly  of  the  omohyoid.  26,  and  27, 
The  branches  from  the  loop  connecting  the  first  and  second  cervical  nerves  which 
unite  to  form  a  cord  that  joins  the  hypoglossal  nerve,  being  contained  within  its 
sheath,  but  leaves  it  again  as  the  descendens  hypoglossi. 


The  auricularis  magTius,  the  small  occipital,  and  the 
superficial  cervical  nerves  are  found  at  the  posterior  border 


76  A  MANUAL   OF  ANATOMY. 

of  the  sternomastoid  muscle,  just  above  its  middle.  The 
first  passes  upward  diagonally  across  the  sternomastoid  to 
the  region  of  the  parotid  gland,  the  second  runs  parallel 
with  the  posterior  border  of  the  sternomastoid  to  the  side 
of  the  head,  and  the  third  crosses  the  muscle  directly  for- 
ward. 

There  are  several  cutaneous  nerves  which  descend 
toward  the  chest. 

They  issue  from  the  posterior  margin  of  the  sternomas- 
toid also,  and  pass  to  the  sternum  {sternal^,  the  clavicle 
iclaviailai'),  and  to  the  shoulder  {acromial^.  For  a  full 
description  of  these  several  nerves,  see  the  cervical  plexus, 
page  89. 

Sternocleidoniastoid.     Fig.  16. 

Origin. — The  inner  head,  from  the  upper  part  of  the 
manubrium  ;  the  outer  head,  from  the  upper  surface  of  the 
inner  third  of  the  clavicle. 

Insertion. — The  mastoid  process  of  the  temporal,  and  the 
outer  half  of  the  superior  curved  line  of  the  occipital  bones. 

Nerve  Supply. — From  the  deeper  branches  of  the  second 
and  third  cervical  nerves,  and  the  spinal  accessory,  which 
passes  through  the  muscle  on  its  way  to  the  trapezius. 

Action. — Acting  from  below.  Both  muscles  will  flex 
the  head  and  neck.  One  will  flex  the  head  laterally,  and 
rotate  the  chin  to  the  opposite  side. 

Acting  from  above.  Will  raise  the  clavicles  and  sternum, 
and  so  act  in  inspiration. 

The  spinal  accessory  and  cervical  branch  to  the  trape- 
zius muscle.  These  two  nerves  will  be  found  as  the  fascia 
is  cleaned  out  between  the  sternomastoid  and  the  trapezius 
muscles.     Figs.  16,  17. 

The  first  issues   from   the  sternomastoid  muscle    at  its 


Fig.  i6.  Dissection  of  Neck.— [For  the  names  of  the  structures  shown  on  the 
face  see  preceding  figures.] — i,  Posterior  belly  of  digastric.  2,  Occipital  artery.  3,  Lesser 
occipital  nerve.  4,  Great  auricular  nerve.  5,  Hypoglossal  nerve.  Note  relation  to  occi- 
pital artery.  6,  External  carotid  artery.  7,  Internal  carotid  artery.  Note  their  mutual 
relations  and  point  of  division  of  tlie  common  carotid.  S,  Superficial  cervical  nerve. 
9,  Spinal  accessory  nerve.  10,  Branch  Irom  cervical  plexus  to  trapezius.  11,  Clavicular. 
12,  Acromial  nerves.  13,  Transverse  cervical  artery.  14,  Facia!  artery  and  its  submental 
branch.  15,  Submaxillary  giand.  Most  of  it  has  been  removed.  16,  Anterior  belly  of  the 
digastric,  resting  upon  the  mylo-hyoid  muscle.  17,  Tendon  of  the  digastric.  18,  Stylo- 
hyoid muscle.  19,  Hyoid  bone.  20,  Thyroid  cartilage.  21,  Anterior  belly  of  the  omo- 
hyoid. 22,  Sternal  nerves.  23,  Sterno-hyoid.  24,  Posterior  belly  of  the  omo-hyoid.  The 
triangles  of  the  neck  can  all  be  easily  recognized.  In  this  connection  consult  Diagram 
No.  VII. 


78  A  MANUAL  OF  ANATOMY. 

middle  and  upper  thirds  and  the  second  from  beneath  the 
muscle  at  its  middle.  They  run  downward  and  backward 
to  disappear  in  front  of  the  trapezius  muscle. 

Digastric.     Figs.  i6,  17. 

Origin. — Posterior  belly,  from  the  digastric  groove  in  the 
temporal  bone.  Anterior  belly,  from  the  under  surface  of 
the  lower  jaw  a  little  external  to  the  symphysis. 

Insertion. — The  two  bellies  are  joined  by  a  central  tendon, 
which  is  fastened  to  the  body  and  greater  cornu  of  the 
hyoid  bone  by  a  process  of  the  deep  cervical  fascia.  This 
fascial  loop  is  lined  by  synovial  membrane. 

The  tendon  also  passes  through  the  stylohyoid  muscle, 
divides  the  insertion  of  that  muscle,  and  by  it  is  aided  in 
keeping  its  place. 

Nerve  Supply. — The  posterior  belly,  by  the  facial.  See 
facial  nerve,  page  61. 

The  anterior  belly  by  the  mylohyoid  branch  of  the 
inferior  dental,  which  is  a  branch  of  the  inferior  maxillary 
nerve. 

Actio7i. — (i)  Posterior  portion.  Raises  and  retracts  the 
hyoid  bone  (and  the  structures  attached  to  it). 

(2)  The  anterior  portion.  Depresses  the  lower  jaw. 
Acting  from  above,  it  will  raise  and  draw  forward  the  hyoid 
bone. 

(3)  Both  portions  acting  will  elevate  the  hyoid  bone  (and 
the  parts  connected  to  it,  especially  the  tongue).  Hence 
the  significance  of  raising  the  lower  jaw  upward  and  forward 
in  anaesthesia,  to  prevent  the  tongue  falling  backward  and 
suffocating  the  patient. 

DISSECTION. 
Divide  the  sternomastoid  muscle  and  the  external  jugular  vein  and  reflect 
their  extremities.      (Always  divide  veins  between  two  cords  tied  firmly  around 


THE  NECK,  ANTERIOR.  Y9 

them.  The  reason  for  this  caution  will  grow  more  apparent  as  the  dissection 
proceeds.) 

Leave  the  spinal  accessory  nerve  passing  through  the  muscle  and  terminat- 
ing in  the  trapezius. 

Incise  the  fascia  which  holds  the  submaxillary  gland  in  position  along  the 
lower  margin  of  the  gland  and  turn  the  gland  upward. 

Clean  the  suprahyoid  and  subhyoid  muscles,  being  careful  in  all  cases  to 
save  the  nerve  supply  to  them. 

The  internal  jugular  vein,  carotid  arteries,  and  the  branches  of  the  external 
carotid,  the  cervical  plexus,  and  all  the  nerves  of  the  deep  region  of  the  neck 
will  have  to  be  dissected  as  far  as  convenient. 

Stylohyoid.     Fig.  17. 

Origin. — From  the  back  and  outer  surface  of  the  styloid 
process  near  its  base. 

Insertion. — Into  the  body  of  the  hyoid  bone  near  the 
greater  cornu.  The  muscle  splits  to  enclose  the  digastric 
tendon. 

Nerve  Supply. — The  facial.     See  page  61. 

Action. — To  raise  and  retract  the  hyoid  bone  (and  the 
parts  connected  to  it). 

Omohyoid.     Figs.  16,  17. 

Origin. — From  the  superior  border  of  the  scapula  near 
the  suprascapular  notch,  and  the  transverse  ligament  cross- 
ing the  notch. 

Insertion. — Into  the  lower  border  of  the  hyoid  bone, 
external  to  the  sternohyoid.  Behind  the  sternomastoid 
the  muscle  becomes  tendinous  and  is  held  downward  by  a 
loop  of  the  deep  cervical  fascia  which  is  attached  to  the 
inner  surface  of  the  clavicle,  first  rib  (its  cartilage),  and  the 
manubrium. 

Nerve  Supply. — The  anterior  portion  by  a  branch  direct 
from  the  descendens  hypoglossi.  The  posterior  portion,  by 
filaments  from  the  loop  of  communication  formed  by  the 
descendens  and  communicans  hypoglossi. 


80  A  MANUAL  OF  ANATOMY. 

Action. — The  hyoid  bone  being  fixed,  slightly  to  raise 
and  draw  fonvard  the  scapula,  to  tense  the  fascia  of  the 
neck  below.  The  scapula  being  fixed,  to  depress  (and 
retract)  the  hyoid  bone. 

Sternohyoid.     Figs.  i6,  17. 

Origin. — From  the  inner  surface  of  the  first  piece  of  the 
sternum,  the  posterior  sternoclavicular  ligament,  and  adja- 
cent portion  of  the  clavicle. 

Insertion. — Into  the  lower  border  of  the  body  of  the 
hyoid  bone. 

Nerve  Supply. — By  filaments  from  the  descendens  and 
communicans  hypoglossi. 

Action. — To  depress  and  fix  the  hyoid  bone. 

Sternothyroid.     Fig.  17. 

Origin. — From  the  inner  surface  of  the  manubrium  below 
and  internal  to  the  sternohyoid,  from  the  cartilage  of  the 
first  rib. 

Insertion. — Into  the  oblique  line  on  the  outer  surface  of 
the  thyroid  cartilage. 

Nerve  Supply. — Same  as  for  the  sternohyoid. 

Action. — To  depress  the  thyroid  cartilage  and  the  hyoid 
bone  above. 

Thyrohyoid.      Figs.  17  and  18. 

Origin. — From  the  oblique  line  on  the  outer  surface  of 
the  thyroid  cartilage. 

Insertion. — Into  the  lower  border  of  the  body  and  greater 
cornu  of  the  hyoid  bone. 

Nerve  Supply. — A  small  branch  directly  from  the  hypo- 
glossal nerve. 

Action. — To  approximate  the  hyoid  bone  and  thyroid 
cartilage,  depressing  the  one  or  elevating  the  other  accord- 
ing to  its  fixed  point. 


THE  XECK,  AXTERIOR.  81 

The  Mylohyoid  Nerve.      Figs.  12,  17. 

This  is  a  small  branch  from  the  inferior  dental  just  before 
it  enters  the  dental  foramen  in  the  lower  jaw.  It  runs 
downward  and  forward,  grooving  the  under  surface  of  the 
lower  jaw,  and  supplies  the  mylohyoid  and  anterior  belly 
of  the  digastric  muscles.  In  its  course  across  the  mylo- 
hyoid muscle  it  is  accompanied  b)-  the  submental  branch 
of  the  facial  arter}'. 

Mylohyoid.      Fig.  17. 

Origin. — From  the  myloh}-oid  ridge  on  the  inner  surface 
of  the  inferior  maxilla. 

Insertion. — Into  the  body  of  the  hyoid  bone,  and  a 
median  raphe  extending  from  the  hyoid  bone  to  the  lower 
jaw. 

Nei've  Supply. — The  mylohyoid  branch  of  the  inferior 
dental  (of  inferior  maxillary). 

Action. — To  raise  the  hyoid  bone,  and  the  parts  con- 
nected to  it,  especially  the  tongue.  To  depress  the  lower 
jaw  if  the  h},-oid  bone  is  fi.xed. 

Having  dissected  out  the  preceding  muscles,  replace 
the  sternomastoid  and  take  up  the  study  of  the  triangles 
of  the  neck,  their  formation  or  boundaries,  the  muscles  or 
parts  which  form  their  floor,  and  most  especially  their  va- 
rious contents  and  their  relations  to  each  other. 

The  Triangles  of  the  Neck.      Figs.  16,  17. 

The  side  of  the  neck  forms  an  irregular  parallelogram 
with  the  following  boundaries. 

Above,  by  the  lower  border  of  the  inferior  maxilla,  the 
mastoid  process  of  the  temporal  bone,  and  a  line  joining 
the  angle  of  the  jaw  with  the  mastoid  process. 

In  front,  by  the  median  line. 

Below,  by  the  top  of  the  manubrium  and  the  clavicle. 


82 


A  MANUAL  OF  ANATOMY. 


Behind,  by  the  anterior  border  of  the  trapezius  muscle. 

This  quadrilateral  space  is  divided  obliquely  from  above 
downward  and  forward  by  the  sternomastoid  muscle  into 
two  triangles,  the  anterior  and  posterior  cervical  triangles. 

The  anterior  triangle  is  further  subdivided  by  the  poste- 
rior belly  of  the  digastric  and  the  anterior  belly  of  the 
omohyoid  muscles  into  three  triangles. 


Diag.  7.    A  Diagram  of  the  Triangles  of  the  Neck.    (/.  S.  H.) 

These  are  from  above  downward,  the  submaxillary, 
superior  and  inferior  carotid  triangles. 

The  Submaxillary  Triangle  is  bounded  by  the  border 
of  the  lower  jaw  and  the  line  from  its  angle  to  the  mastoid 
process,  by  the  posterior  belly  of  the  digastric  (and  the 
stylohyoid),  and  by  the  median  line.     (The  student    can 


THE  NECK,  ANTERIOR.  83 

locate  the  relative  positions  of  these  boundaries  without 
further  particulars.) 

Its  floor  is  formed  by  the  anterior  belly  of  the  digastric, 
the  mylohyoid,  the  hyoglossus,  the  styloglossus,  superior 
constrictor,  and  the  stylopharyngeus  muscles. 

Within  it  are  found  arteries,  internal  and  external  caro- 
tids, facial,  and  its  cervical  branches. 

Veins :  Internal  jugular,  facial,  anterior  and  posterior 
divisions  of  the  temporomaxillary  vein  or  sinus. 

Nerves :  Inframaxillary  branch  of  facial,  mylohyoid, 
pneumogastric,  and  glossopharyngeal  and  hypoglossal. 

Glands :  Submaxillary,  deep  portion  of  parotid,  and 
lymphatic  glands. 

The  Superior  Carotid  Triangle.      ("  Triangle  of  Election.'"') 

Boundaries. — By  the  posterior  belly  of  the  digastric,  the 
anterior  belly  of  the  omohyoid,  and  the  anterior  border 
of  the  sternomastoid. 

Floor  is  formed  by  the  hyoglossus,  thyrohyoid,  middle 
and  inferior  constrictors  ;  hyoid  bone  and  thyroid  cartilage. 

Its  Contents. — Arteries  :  Common,  external  and  internal 
carotids  ;  superior  thyroid,  lingual,  facial,  occipital,  and 
ascending  pharyngeal. 

Veins  :  Internal  jugular,  veins  corresponding  to  the 
above  branches  of  the  external  carotid. 

Nerves  :  Inframaxillary  branch  of  facial,  superficial 
cervical,  descendens  and  communicans  hypoglossi,  hypo- 
glossal, pneumogastric,  spinal  accessory,  and  superior 
laryngeal. 

Parts  of  the  larynx  and  pharynx  and  lymphatic  glands. 

The  Inferior  Carotid  Triang-le.     ("  Triangle  of  Necessity.'") 
Boundaries. — By  the  median  line,  anterior  border  of  the 
sternomastoid,  and  anterior  belly  of  the  omohyoid. 


84  A  MANUAL  OF  ANA  TOMY. 

Floor  is  formed  by  the  scalenus  anticus  and  longus  colli 
muscles. 

Contents. — Arteries  :  Common  carotid,  inferior  thyroid, 
and  vertebral. 

Veins:  Internal  jugular,  vertebral,  middle  thyroid. 

Nerves :  Superficial  cervical,  pneumogastric,  recurrent 
laryngeal,  descendens  and  communicans  hypoglossi,  sym- 
pathetic. 

Parts  of  the  larynx,  trachea,  thyroid  gland,  lymphatic 
glands,  sternohyoid,  and  sternothyroid  muscles. 

The  posterior  triangle  is  divided  by  the  posterior  belly  of 
the  omohyoid  into  the  occipital  and  subclavian  triangles. 

The  Occipital  Triangle. 

Boundaries. — By  the  posterior  border  of  the  sterno- 
mastoid,  the  anterior  border  of  the  trapezius,  and  the  pos- 
terior belly  of  the  omohyoid  muscles. 

Floor  is  formed  by  the  splenius  capitis  et  colli,  the 
levator  anguli  scapulae,  scalenus  medius  and  posticus. 

Contents. — Arteries  :  Occipital,  muscular,  superficial  cer- 
vical, and  transverse  cervical. 

Veins  :   Posterior  external  jugular,  transverse  cervical. 

Nerves :  The  ascending  and  descending  branches  of 
the  cervical  plexus,  and  the  spinal  accessory. 

Lymphatic  glands. 

The  Subclavian  Triangle  {Mohrenheim' s  Fossa). 

Boundaries. — The  posterior  border  of  the  sternomastoid, 
the  posterior  belly  of  the  omohyoid,  and  the  clavicle. 

Floor  is  formed  by  the  scalenus  posticus  and  medius. 

Contents. — Arteries :  Second  and  third  portions  of  the 
subclavian,  and  its  suprascapular,  transverse  cervical,  and 
superior  intercostal  (and  usually  the  posterior  scapular,  see 
page  1 1 3)  branches. 


THE  A'ECK,  AXTEKIOR. 


85 


Veins:  External  jugular,  transverse  cervical,  supra- 
scapular, and  subclavian. 

Nerves :  Descending  cervical  branches,  beginning  of  the 
brachial  plexus,  muscular  branches  from  the  lower  four  cer- 
vical nerves  before  the  plexus  is  formed,  the  phrenic  nerve. 

Other  parts :  Scalenus  anticus  muscle,  and  lymphatic 
glands. 

The  Ling-ual  Triangle. 

This  is  a  subdivision  of  the  submaxillary  triangle. 


,  External Utr-otid 


Diag.  8,    A  Diagram  of  the  Lingual  Triangle.    (/.  S.  H.) 

Boundaries. — In  front,  the  posterior  margin  of  the  mylo- 
hyoid muscle.  Behind,  the  posterior  belly  of  the  digastric 
and  the  stylohyoid  muscle.     Above,  the  hypoglossal  nerve. 

The  floor  is  formed  by  the  hyoglossus  muscle,  and  the 
lingual  artery  is  found  under  the  muscle  after  dividing  its 
fibres  transversely. 

The  Submaxillary  Gland.      Figs.  15  and  16. 

The  submaxillary  gland  is  the  second  in  size  of  the  sali- 
vary glands.      It  lies  under  the  lower  jaw,  and  is  covered 


86  A  MANUAL   OF  ANATOMY. 

by  the  platysma  and  deep  cervical  fascia  which  forms  its 
capsule.  Behind  are  the  posterior  belly  of  the  digastric, 
the  stylohyoid  muscles,  and  the  stylomaxillary  ligament ; 
in  front,  the  anterior  belly  of  the  digastric  ;  below,  the 
tendon  of  the  digastric,  and  the  hyoid  bone. 

Internally  the  gland  lies  upon  the  mylohyoid,  hyoglos- 
sus,  and  styloglossus  muscles.  The  mylohyoid  separates 
the  submaxillary  from  the  sublingual  gland.  Around  the 
posterior  border  of  the  mylohyoid  muscle  a  deep  portion 
of  the  submaxillary  gland  extends  forward,  and  from  this 
deep  portion  the  duct  (Wharton's)  passes  forward  and  in- 
ward to  open  in  the  floor  of  the  mouth  at  the  summit  of  a 
small  papilla  at  the  side  of  the  frsenum  of  the  tongue.  The 
duct  is  about  two  inches  long.      Fig.  i8. 

Relations  about  the  Submaxillary  Gland. — The  facial  vein 
and  inframaxillary  branch  of  the  facial  nerve  cross  the  outer 
surface  of  the  gland. 

The  facial  artery  deeply  grooves  the  posterior  and  upper 
portion  of  the  gland. 

The  submental  branch  of  the  facial  artery  and  the  mylo- 
hyoid nerve  run  together  along  its  upper  border. 

Wharton's  duct  lies  above  the  lingual  nerve  (which  ac- 
companies it  to  the  tongue). 

Between  the  lingual  nerve  and  gland  lies  the  submaxil- 
lary ganglion. 

The  arterial  supply  is  from  the  facial  (submaxillary 
branches)  and  lingual. 

The  nerves  are  derived  from  the  submaxillary  ganglion, 
mylohyoid,  and  sympathetic. 

For  the  submaxillary  ganglion,  see  page  119. 

DISSECTION. 
Divide  the  tendon  of  the  digastric  on  either  side  of  the  loop  which  binds  it 
to  the  hyoid  bone,  and  the  stylohyoid  at  its  insertion. 


l26  127  128  129 
Fig.  17.  Dissection  of  Neck. — i,  Posterior  auricular  arterj'.  2,  Sterno-mastoid 
muscle  divided  and  drawn  upward  and  backward.  Shows  the  course  of  the  spinal 
accessory  nerve  through  it.  3,  Spinal  accessory  nerve.  4,  Occipital  artery.  5,  Hypo- 
glossal nerve.  6,  Lesser  occipital  nerve.  7,  Descendens  hypoglossi  lying  upon  the 
common  carotid.  In  this  subject  the  nerve  seems  to  be  a  branch  (uses  the  sheath)  of  the 
pneumogastric  nerve.  8,  Commuiiicans  hypoglossi.  In  this  connection  consult  Diagram 
No.  \'I.  9,  Pneumogastric.  10,  Spinal  accessory.  It  is  seen  to  be  joined  by  a  branch 
from  the  cervical  plexus.  11,  Phrenic  nerve.  12.  Subclavian  nerve.  13,  Brachial  plexus. 
14,  Transverse  cervical  artery.  15,  Transverse  facial  artery.  16,  Mylo-hyoid  nerve,  and 
behind  it  the  submental  branch  of  the  facial  artery.  17,  Mylo-hyoid  muscle.  18,  Hyo- 
glossus  muscle.  19,  Lingual  artery.  Consult  Diagram  No.  VIII.  20,  Superior  laryngeal 
nerve.  21,  Thyro-hyoid  muscle.  22,  Superior  thyroid  artery.  23,  Anterior  belly  of  the 
omo-hyoid.  24,  Sterno-hyoid  muscle.  25,  Sterno-thyroid  muscle.  26,  Fascia  binding 
the  tendon  of  the  omo-hyoid  in  place.  27,  Subclavian  arterj-.  28,  Posterior  belly  of  the 
omo-hyoid.    29,  Posterior  scapular  artery. 


88  A  MANUAL   OF  ANATOMY. 

Divide  the  mylohyoid  along  the  median  raphe  and  at  its  insertion  into  the 
hyoid  bone,  and  reflect  the  several  parts  of  the  muscles. 

The  Hypoglossal  Nerve.      Figs.  lo,  i6,  17,  18. 

The  hypoglossal  nerve  leaves  the  skull  through  the  ante- 
rior condyloid  foramen,  winds  outward  around  the  ganglion 
of  the  trunk  of  the  pneumogastric  nerve  from  behind  forward, 
passes  between  the  internal  jugular  vein  and  the  internal  caro- 
tid artery,  appears  at  the  lower  border  of  the  digastric, 
turns  forward  around  the  occipital  artery  and  across  the 
internal  and  external  carotids,  and  extends  into  the  muscles- 
of  the  tongue  (resting  upon  the  hyoglossus  and  under 
the  mylohyoid),  where  it  breaks  up  into  its  terminal 
branches. 

For  the  part  that  the  nerve  takes  in  forming  the  lingual 
triangle,  see  page  85. 

As  the  hypoglossal  nerve  crosses  the  ganglion  of  the 
pneumogastric,  it  receives  filaments  from  that  nerve,  the 
sympathetic,  and  a  branch  from  the  first  and  second  cervi- 
cal nerves.     See  Cervical  Plexus,  page  89. 

Branches. — The  descendens  hypog-lossi.  This  is  com- 
posed of  the  fibres  derived  from  the  cervical  plexus  (first 
and  second).  It  leaves  the  hypoglossal  nerve  as  it  is  turn- 
ing around  the  occipital  artery  (may  come  off  much  higher) 
and  runs  forward  and  downward  upon  the  sheath  of  the 
carotid,  where  it  is  joined  (in  the  middle  of  the  neck)  by  the 
communicantes  hypoglossi,  forming  the  ansa  hypoglossi 
(hypoglossal  loop). 

The  descendens  hypoglossi  gives  off  a  small  branch  to 
the  anterior  belly  of  the  omohyoid  muscle  before  the  for- 
mation of  the  loop.  From  the  loop  branches  are  supplied 
to  the  posterior  belly  of  the  omohyoid,  the  sternohyoid, 
and  sternothyroid  muscles. 

The  hypoglossal  also  gives  off  a  small  branch  just  below 


THE  NECK,  ANTERIOR.  89 

the  descendens  hypoglossi,  which  supphes  the  thyrohyoid 
muscle,  and  a  recurrent  twig  to  the  styloglossus. 

Under  the  mylohyoid  the  hypoglossal  gives  branches  to 
the  hyoglossus,  geniohyoid,  geniohyoglossus,  genioglossus, 
and  the  muscular  substance  of  the  tongue. 

The  Cervical  Plexus.      Figs.  i6,  17,  18. 

The  cervical  plexus  is  formed  by  the  anterior  branches 
of  the  four  upper  cervical  nerves,  which  appear  along  the 
side  of  the  neck  between  the  prevertebral  and  lateral  sets 
of  muscles,  and  are  connected  in  series  by  interlacing 
branches. 

A  diagrammatic  representation  of  the  plexus  is  given  on 
page  75.      Diag.  6. 

Bi'anclies. — From  the  loop  joining  the  first  and  second 
nerves  is  given  off: — 

(i)  A  branch  which  passes  forward  to  join  the  hypo- 
glossal nerve. 

(2)  From  the  second  nerve  is  given  off  the  small  occip- 
ital. 

(3)  From  the  second  and  third  nerves  are  given  off 
branches  to  form  the  great  auricular  (4)  the  superficial 
cervical  and  (5)  the  communicantes  hypoglossi.  The 
second  and  third  are  joined  by  a  loop. 

From  the  third  proceeds  the  (6)  nerve  to  the  trape- 
zius. 

From  the  third  and  fourth  the  (7)  sternal,  (8)  clavi- 
cular,  (9)  and  acromial  branches. 

From  the  fourth  (and  fifth,  of  brachial  plexus)  arises  (10) 
the  phrenic. 

(11)  Muscular  branches  are  derived  from  the  first  for  the 
rectus  capitis  lateralis  and  the  rectus  capitis  anticus  minor  ; 
from   the   first   and   second,  for  the   rectus   capitis   anticus 


90  A  MANUAL   OF  ANATOMY. 

major ;  from  the  second,  to  the  sternomastoid  ;  from  the 
third,  to  the  scalenus  medius  and  the  levator  anguli  scapulae  ; 
from  the  fourth,  to  the  same. 

The  Branches  of  the  Cervical  Plexus. 

(i)  The  branch  to  the  hypoglossal :  After  joining  the 
hypoglossal  nerve  this  branch  passes  with  it  for  a  short  dis- 
tance. Some  of  the  fibres  continue  onward  to  supply  the 
geniohyoid,  thyrohyoid,  and  anterior  belly  of  the  omo- 
hyoid. The  greater  part  of  the  fibres  leave  the  hypo- 
glossal nerve  as  the  descejidens  hypoglossi,  form  a  loop 
below  with  the  (5)  communicantes  hypoglossi,  and  supply 
the  posterior  belly  of  the  omohyoid,  sternohyoid,  and  sterno- 
thyroid muscles. 

(2)  The  small  occipital :  This  issues  at  the  middle  of  the 
posterior  border  of  the  sternomastoid  muscle  along  with 
the  superficial  cervical  and  the  great  auricular,  turns 
upward  parallel  with  this  border  of  the  sternomastoid  to 
supply  branches  to  the  upper  portion  of  the  ear  (auricular), 
to  the  skin  over  the  mastoid  process  (mastoid),  and  to  the 
scalp  (occipital). 

(3)  The  great  auricular  :  This  is  found  at  the  middle  of 
the  posterior  border  of  the  sternomastoid,  passes  vertically 
upward  to  supply  the  region  of  the  parotid  gland  (facial), 
lower  back  part  of  the  ear  (auricular),  and  the  mastoid 
region  (mastoid), 

(4)  The  superficial  cervical  :  Comes  from  the  middle  of 
the  posterior  margin  of  the  sternomastoid,  passes  forward 
transversely  across  the  muscle  and  supplies  the  platysma, 
the  skin  of  the  antero-lateral  region  of  the  neck,  and  forms 
a  loose  plexiform  interlacement  with  the  inframaxillary 
branch  of  the  facial. 

(5)  The  communicantes  hypoglossi :  The  branch  from 
the  second  passes  downward,  joins   that  from  the  third,  the 


THE  NECK,  ANTERIOR.  91 

united  branch  then  passes  downward  and  forward,  usually 
over  the  internal  jugular  vein  to  unite  upon  the  common 
carotid  artery  with  the  descendens  hypoglossi.  For  the 
distribution  see  (i). 

(6)  The  muscular  branch  to  the  trapezius  muscle  appears 
on  the  posterior  border  of  the  sternomastoid  at  its  middle, 
passes  backward  to  the  trapezius,  and  with  the  spinal  acces- 
sory, which  courses  at  a  higher  level,  is  distributed  to  this 
muscle. 

(7),  (8),  (9)  The  branches  to  the  integument  over  the 
sternum,  clavicle,  and  acromial  regions.  They  become 
superficial  at  the  posterior  border  of  the  sternomastoid 
muscle  and  descend  to  their  distribution.  The  supra- 
sternal to  the  integument  over  the  first  piece  of  the  sternum  ; 
the  supraclavicular,  to  the  skin  over  the  front  of  the  clavi- 
cle (and  chest  as  low  as  the  fourth  rib)  ;  and  the  supra- 
acromial  to  the  region  of  the  shoulder. 

(10)  Tlie  pJirenic.     For  phrenic  nerve,  see  page  100. 

The    Spinal    Accessory    Nerve.     Figs.    10,    11,    12,    16, 

17- 
This  will  be  found  issuing  under  the  posterior  belly  of 
the  digastric  muscle.  It  continues  downward  through  the 
sternomastoid  muscle,  in  the  substance  of  which  it  forms 
a  plexiform  junction  with  a  branch  from  the  second  cervical 
nerve  for  the  supply  of  the  muscle,  then  appears  at  the 
posterior  border  of  the  sternomastoid  and  extends  down- 
ward and  backward  to  the  anterior  surface  of  the  trapezius, 
to  which  (with  branches  from  the  third  and  fourth  cervical 
nerves)  it  is  distributed.  The  deep  course  of  the  nerve 
after  it  comes  through  the  central  compartment  of  the  jugu- 
lar foramen  (with  the  ninth  and  the  tenth  nerves)  is  down- 
ward and  backward  across  the   internal  jugular  vein  and 


92  A  MANUAL   OF  ANA  TOMY. 

under  the   occipital  artery,  stylohyoid   and  posterior  belly 
of  the  digastric  muscles. 

The  Internal  Jugular  Vein.      Fig.  15. 

This  vein  is  formed  just  at  the  base  of  the  skull  by  the 
junction  of  the  inferior  petrosal  (anterior)  and  lateral  (pos- 
terior) sinuses.      Diags.  i,  5. 

Its  course  is  along  the  posterior  surface  of  the  internal 
and  common  carotid  arteries  to  behind  the  sternoclavicular 
articulation,  where  it  is  joined  by  the  subclavian,  to  form 
the  innominate  vein.     See  page  99. 

In  its  course  it  receives  veins  corresponding  to  the 
branches  of  the  external  carotid  artery. 

It  is  also  connected  by  communicating  veins  with  the 
external  and  internal  jugular  veins. 

DISSECTION. 

The  internal  jugular  vein  should  be  tied  off  and  divided  about  two  inches 
from  the  clavicle,  and  as  high  toward  the  head  as  possible,  and  the  intervening 
portion  with  all  its  tributaries  removed. 

Keep  in  mind  that  the  thoracic  duct  opens  into  the  angle  at  the  junction  of 
the  internal  jugular  and  the  subclavian  veins.  The  description  of  the  duct  is 
given  with  the  dissection  of  the  thorax. 

The  External  Carotid.      Figs.  16,  17,  18. 

This  is  the  outer  branch  of  the  common  carotid.  It  ex- 
tends from  the  bifurcation  of  the  common  carotid  at  the 
level  of  the  upper  border  of  the  thyroid  cartilage  to  behind 
the  neck  of  the  inferior  maxilla,  where  it  divides  into  the 
temporal  and  internal  maxillary  arteries. 

At  its  beginning  it  lies  anterior  to  the  internal  carotid, 
and  at  its  termination  superficial  to  the  same. 

The  natural  guide  to  the  artery  is  the  anterior  border  of 
the  sternomastoid  muscle. 

Relatiojis,  External,  or  superficial. — Skin,  platysma,  deep 


THE  NECK,  ANTERIOR.  93 

fascia,  parotid  gland ;  the  sternomastoid  overlaps  the 
artery  to  a  greater  or  less  extent  from  behind  forward. 

It  is  crossed  from  above  downward  by  the  branches  of  the 
facial  nerve,  the  temporomaxillary  vein,  stylohyoid,  and 
posterior  belly  of  the  digastric  muscles,  the  facial  and  lingual 
veins,  and  the  hypoglossal  nerve. 

Internal,  or  centrally,  the  internal  carotid,  from  which 
it  is  separated  by  the  stylopharyngeus,  styloglossus 
muscles,  the  glossopharyngeal,  and  pharyngeal  branch 
of  pneumogastric  nerves,  the  posterior  part  of  the  paro- 
tid gland,  and  the  stylomastoid  ligament.  The  superior 
laryngeal  nerve  lies  behind  both  internal  and  external 
carotids. 

Anterior,  or  in  front,  the  hyoid  bone,  pharynx,  stylo- 
maxillary  ligament,  ramus  of  jaw. 

Posterior,  or  behind,  the  internal  carotid  for  a  short  dis- 
tance at  its  beginning,  the  hypoglossal  nerve,  the  occipital 
artery,  mastoid  process. 

Brandies. — (i)  The  Superior  Thyroid  :  This  is  the  first 
branch  from  the  anterior  surface  of  the  artery. 

Its  course  is  forward  beneath  the  great  cornu  of  the 
hyoid  bone,  then  downward  and  forward  to  the  upper  part 
of  the  thyroid  gland. 

In  its  course  it  gives  off  branches  to  the  larynx,  pharynx, 
thyroid  gland,  trachea,  and  oesophagus ;  also,  muscular 
branches  to  the  sternomastoid,  sternohyoid,  sternothyroid, 
thyrohyoid,  and  inferior  constrictor. 

The  named  branches  are  {a)  the  hyoid,  which  passes 
transversely  forward  between  the  hyoid  bone  and  the  thy- 
roid cartilage.  (Ij)  The  sternomastoid,  to  that  muscle. 
This  branch  crosses  the  carotid  sheath,  {c)  The  superior 
laryngeal,  which  accompanies  the  nerve  of  the  same  name 
into  the  interior  of  the  larynx,     {d^  The  crieothyroid.      Of 


94  A  MANUAL  OF  ANATOMY. 

interest  because  it  anastomoses  with  its  fellow  from  the 
other  side  across  the  cricothyroid  membrane,  and  must  be 
divided  in  laryngotomy,  or  laryngotracheotomy. 

(2)  The  Lingual  Artery :  The  second  branch  from  the 
front  of  the  external  carotid.  Its  course  is  forward  and 
upward  around  the  great  cornu  of  the  hyoid  bone,  then 
beneath  the  hyoglossus  muscle,  then  under  the  tongue  (as 
the  ranine  artery)  to  its  tip. 

The  artery  is  reached  for  purposes  of  Hgation  through 
the  lingual  triangle.     See  page  85. 

Branches  of  the  Lingual :  {a)  The  hyoid ;  this  runs  for- 
ward over  the  hyoglossus  muscle  just  above  the  hyoid 
bone.  {U)  The  doj^sal  a7'tery  of  the  tongue  is  a  branch 
from  the  lingual  under  the  hyoglossus  muscle  ;  it  passes 
upward  to  the  back  of  the  tongue.  It  supplies  not  only 
the  tongue  but  small  branches  to  the  tonsil  and  fauces. 
(r)  The  sublingual  is  given  off  at  the  anterior  border  of  the 
hyoglossus  muscle,  passes  forward  under  the  mylohyoid 
muscle  to  the  sublingual  gland,  floor  of  the  mouth,  and  in 
its  course  supplies  the  adjacent  muscles.  The  artery  of  the 
fraenum  is  a  branch  from  the  sublingual.  {(T)  The  ranine, 
or  the  last  portion  of  the  lingual  along  the  under  surface 
of  the  anterior  portion  of  the  tongue,  to  its  tip.  Supplies 
the  tongue  and  the  surrounding  muscles. 

(3)  The  Facial  Artery  (in  the  neck).  Arises  from  the 
front  of  the  external  carotid  as  the  third  branch,  or  with 
the  hngual  by  a  branch  common  to  both.  It  takes  a 
tortuous  course  upward  and  forward,  under  the  posterior 
belly  of  the  diagastric  and  the  stylohyoid  muscles,  through 
the  upper  and  back  part  of  the  submaxillary  gland,  which  it 
deeply  grooves,  then  turns  upward  on  to  the  face,  over  the 
lower  jaw,  just  in  front  of  the  masseter  muscle.  For  its 
course  in  the  face,  see  page  64. 


THE  NECK,  ANTERIOR.  95 

Between  the  facial  artery  and  vein  are  found  these  struc- 
tures, the  posterior  belly  of  the  diagastric,  the  stylohyoid 
muscles,  and  the  submaxillary  gland. 

Branches  of  the  facial  in  the  neck  :  {a)  The  ascending 
palatine,  {b)  The  tonsillar.  These  branches  pass  upward 
to  supply  the  palate,  fauces,  tonsils,  and  pharynx ;  the 
former  is  behind,  the  latter  in  front,  of  the  styloglossus 
muscle,  which  separates  them,  [c)  The  glandular  or  sub- 
maxillary branches  to  that  gland,  as  the  facial  passes 
through  it.  {d)  The  submental,  a  considerable  branch 
which  runs  forward  under  the  lower  jaw  and  upon  the 
mylohyoid  muscle  (being  accompanied  by  the  mylohyoid 
nerve),  supplies  the  adjacent  muscles,  and  turns  upward 
over  the  chin  to  anastomose  with  the  mental  (of  the  inferior 
dental)  and  the  inferior  labial  (of  the  facial). 

Besides  the  chain  of  anastomoses  which  is  formed  by 
the  branches  of  the  inferior  thyroid,  lingual,  and  facial  upon 
the  same  side  of  the  neck  and  face,  all  these  branches 
which  pass  forward  to  the  median  line  inosculate  across  the 
median  line  with  similar  branches  from  the  other  side.  This 
also  holds  for  the  nasal,  frontal,  and  supra-orbital  branches 
of  the  ophthalmic.      See  page  65. 

(4)  The  Occipital  Artery  is  given  off  from  the  posterior 
aspect  of  the  external  carotid.  It  runs  upward  and  back- 
ward under  the  posterior  belly  of  the  digastric  to  a  point 
between  the  transverse  process  of  the  atlas  and  the  mastoid 
process.  Here  it  is  covered  by  the  sternomastoid,  splenius 
capitis,  and  origin  of  the  digastric.  Then  its  course  is  back- 
ward in  the  occipital  groove,  where  it  will  be  found  when 
dissecting  the  back.  See  page  130.  The  artery  is  crossed 
by  the  hypoglossal  nerve,  which  winds  downward  and  for- 
ward across  the  artery.  In  the  anterior  portion  of  the  neck 
it  gives  off  muscular  branches  to  the  adjacent  muscles  ;  the 


96  A  MANUAL   OF  ANATOMY. 

one  to  the  sternoniastoid  is  of  some  size  and  is  the  only 
one  named. 

The  remaining  branches  of  the  occipital  are  given  on 
page  130. 

(5)  The  Posterior  Auricular  Artery  :  See  Dissection  of 
the  Face,  page  65. 

This  is  the  second  branch  from  the  back  of  the  external 
carotid.  It  is  given  off  just  above  the  occipital,  runs  up- 
ward and  backward  between  the  spinal  accessory  and  facial 
nerves,  and  through  the  parotid  gland  to  the  groove 
between  the  external  auditory  meatus  and  the  mastoid 
process,  and  supplies  branches  to  the  ear  and  the  scalp 
behind  it.  From  the  posterior  auricular  is  given  off  the 
stylomastoid  branch  which  enters  the  foramen  of  that 
name. 

(6)  The  Ascending  Pharyngeal :  This  is  the  first  branch 
of  the  external,  and  comes  off  in  the  angle  between  it 
and  the  internal  carotid. 

It  is  a  long,  slender  artery,  which  runs  upward  between 
the  pharynx,  internal  carotid,  and  spine  to  the  base  of  the 
skull.  It  supphes  fine  branches  to  the  pharynx,  front  of 
the  spine,  palate,  and  posterior  meningeal,  which  reach  the 
interior  of  the  skull  through  the  middle  lacerated,  jugular, 
and  anterior  condyloid  foramina. 

Geniohyoid.     Fig.  18. 

Origin. — From  the  lower  genial  tubercle  of  the  inferior 
maxilla. 

Insertion. — Into  the  upper  surface  of  the  hyoid  bone, 
close  to  the  middle  line. 

Nerve  Supply. — The  hypoglossal. 

Action. — To  raise  the  hyoid  bone  or  to  depress  the 
lower  jaw,  depending  upon  which  is  the  fixed  point. 


THE  NECK,  ANTERIOR.  97 

Geniohyoglossus.     Fig.  i8. 

Origin. — From  the  superior  genial  tubercle. 

Insertion. — Into  the  body  of  the  hyoid  bone,  the  tongue 
from  its  tip  to  its  base  just  outside  of  the  median  plane,  and 
into  the  side  of  the  pharynx. 

Nerve  Supply. — The  hypoglossal. 

Action. — To  depress  the  lower  jaw,  to  raise  the  hyoid 
bone,  to  protrude  the  tongue  (by  its  posterior  fibres),  to 
depress  and  protrude  the  middle  of  the  tongue  (by  its  mid- 
dle fibres),  and  to  retract  the  tip  of  the  tongue  (by  its  ante- 
rior fibres). 

Hyoglossus.      Figs.  17  and  18. 

Origi)i. — From  the  body  and  great  cornu  of  the  hyoid 
bone. 

Insertion. — Into  the  substance  of  the  posterior  half  of  the 
tongue  external  to  the  geniohyoglossus. 

Nerve  Supply. — The  hypoglossal. 

Action. — To  depress  the  sides  of,  and  retract  the  whole 
tongue. 

Styloglossus.      Fig.   18. 

Origin. — From  the  front  of  the  lower  portion  of  the 
styloid  process. 

Insertion. — Into  the  side  of  the  tongue,  interlacing  with 
the  hyoglossus. 

Nerve  Supply. — The  hypoglossal. 

Action. — To  retract  the  tongue  and  elevate  its  sides. 

Stylopharyngeus.      Fig.  18. 

Origin. — From  the  inner  surface  of  the  base  of  the 
styloid  process. 

Insertion. — Passing    between    the    superior    and    middle 
constrictor  muscles,  it  is  inserted  into  the  posterior  border 
of  the  thyroid  cartilage  and  wall  of  the  pharynx. 
7 


98  A  MANUAL   OF  ANATOMY. 

Nerve  Supply, — The  glossopharyngeal. 
Action. — To  raise  the  pharynx  and  larynx. 

The  Glossopharyngeal  Nerve.      Figs.  lO,  ii,  i8. 

This  is  found  in  the  dissection  of  the  neck,  as  it  curves  for- 
ward around  the  outer  side  of  the  stylopharyngeus  muscle. 

It  leaves  the  skull  through  the  jugular  foramen,  in  the 
central  compartment,  with  the  tenth  and  eleventh  nerves. 

It  runs  forward  between  the  internal  jugular  vein  and  the 
internal  carotid  artery,  then  winds  around  the  outer  border 
•of  the  stylopharyngeus  muscle  to  terminate  in  the  under 
surface  of  the  hyoglossus  muscle. 

Branches. — The  glossopharyngeal  nerve  supplies  the 
stylopharyngeus  muscle,  then  gives  off  small  filaments  to 
help  form  the  pharyngeal  plexus,  and  to  supply  the  tonsil 
and  tongue. 

The  Internal  Carotid  Artery.     Figs.  i6,  17,  18. 

This  begins  at  the  same  point  as  the  external,  viz.  :  at 
the  bifurcation  of  the  common  carotid,  at  the  level  of  the 
upper  border  of  the  thyroid  cartilage. 

It  passes  directly  upward  to  the  base  of  the  skull,  being 
internal  to  the  external  carotid,  and  separated  from  it  by 
the  structures  mentioned  on  page  93. 

Relations. — See  the  relations  of  the  external  carotid,  page 

92. 

In  the  beginning  of  its  course  the  artery  lies  in  the  su- 
perior carotid  triangle,  and  then  within  the  submaxillary 
triangle.  As  it  passes  upward  it  rests  upon  the  rectus 
capitis  anticus  major,  the  superior  cervical  sympathetic 
ganglion,  and  the  pneumogastric  nerve.  Behind  it  is  the 
internal  jugular  vein,  which,  near  the  base  of  the  skull,  is 
separated  from  the  artery  by  the  hypoglossal,  pneumogas- 
tric, glossopharyngeal,  and  spinal  accessoiy  nerves. 


THE  NECK,  ANTERIOR.  99 

In  front  of  the  artery  is  the  pharynx  and  the  tonsil,  from 
which  it  is  separated  by  the  superior  constrictor  muscle. 

The  course  of  the  artery  into  the  skull  is  through  the 
carotid  canal,  within  the  petrous  portion  of  the  temporal 
bone,  and  then  by  the  upper  part  of  the  foramen  lacerum 
medium,  beyond  which  it  enters  the  cavernous  sinus.  See 
pages  43,  53,  and  158. 

The  artery  gives  off  no  branches  in  the  cervical  part  of 
its  course. 

DISSECTION. 

Leave  the  remaining  structures  beneath  the  lower  jaw  for  dissection  with 
the  deep  face  and  turn  to  the  parts  at  the  base  of  the  neck. 

Working  carefully  from  the  superficial  to  the  deep  structures,  clean  them  in 
order,  all  the  time  noticing  their  mutual  relations,  which  are  many  and  com- 
plex, but  which  can  be  far  better  understood  and  remembered  if  in  the  dissec- 
tion the  student  will  only  take  the  time  to  notice  and  repeat  them  to  himself 
as  his  work  proceeds. 

Divide  the  omohyoid  near  its  middle,  the  sternohyoid  and  sternothyroid 
near  the  sternum,  and  reflect  them. 

The  Subclavian  Vein.      Fig.  18. 

The  subclavian  vein  extends  from  the  lower  border  of 
the  first  rib,  beyond  which  it  is  called  the  axillary,  to  behind 
the  sternoclavicular  articulation,  where  it  ends  by  joining 
with  the  internal  jugular  to  form  the  innominate  vein. 

It  lies  in  front  and  slightly  below  the  subclavian  artery, 
from  which  it  is  separated  by  the  scalenus  anticus  muscle 
and  phrenic  nerve. 

Tributaries. — The  external  jugular,  and  sometimes  the 
anterior  jugular  or  the  cephalic. 

The    Transverse    Cervical    and    Suprascapular    Veins. 

Fig.  15. 

These  veins  are  double  (venae  comites)   and   return   the 

blood  from  the  region  supplied  by  their  respective  arteries. 

Near  their  terminus  each  pair  unites  to  form  a  single  trunk, 


100  A  MANUAL  OF  ANATOMY. 

which  opens  into  the  lower  part  of  the  external  jugular 

vein.     See  page  74. 

The  Phrenic  Nerve.      Figs,  t/,  18. 

The  phrenic  nerve  is  formed  by  branches  from  the  third, 
fourth,  and  fifth  cervical  nerves.  The  fourth  is  the  constant 
branch,  the  fifth  may  be  present,  but  the  branch  from  the 
third  is  very  inconstant. 

The  phrenic  descends  obliquely  across  the  front  of  the 
scalenus  anticus  muscle,  passes  between  the  subclavian 
artery  and  vein,  and  enters  the  chest  over  the  front  of  the 
internal  mammary  artery.     See  thorax  for  rest  of  course. 

Scalenus  Anticus.      Fig.  18. 

Origin. — From  the  anterior  tubercles  of  the  transverse 
processes  of  the  third,  fourth,  fifth,  and  sixth  cervical  ver- 
tebrae. 

Insertion. — Into  the  scalene  tubercle  upon  the  upper  sur- 
face and  inner  border  of  the  first  rib. 

Nerve  Stipply. — From  the  anterior  divisions  of  the  fourth, 
fifth,  and  sixth  cervical  nerves  close  to  the  intervertebral 
foramina. 

Action. — Both  muscles,  acting  from  below,  will  flex  the 
neck  ;  one  acting,  will  rotate  the  neck  to  the  opposite  side 
and  flex  the  neck  laterally.  Acting  from  above,  the  mus- 
cles will  raise  and  fix  the  first  rib,  so  aiding  in  inspiration. 

Scalenus  Medius.      Fig.  18. 

Origin. — From  the  posterior  tubercles  of  the  transverse 
processes  of  the  lower  six  cervical  vertebrae  (sometimes 
the  atlas  also). 

Insertion. — Into  the  upper  surface  of  the  first  rib  between 
the  subclavian  groove  and  the  tuberosity. 

Nerve  Supply. — The  branches  from  the  posterior  divisions 
of  the  cervical  nerves. 


THE  NECK,  ANTERIOR.  101 

Action. — They  flex  the  neck  laterally  if  acting  from 
below ;  if  from  above,  they  raise  and  fix  the  first  rib,  thus 
aiding  inspiration. 

Scalenus  Posticus.      Fig.  76. 

Origin. — From  the  posterior  tubercles  of  the  transverse 
processes  of  the  lower  two  or  three  cervical  vertebrae. 

Insertion. — Into  the  outer  surface  of  the  second  rib 
behind  the  insertion  of  the  serratus  magnus. 

Nerve  Supply. — The  three  lower  cervical  nerves. 

Action. — As  slight  lateral  flexor  of  the  lower  cervical 
vertebrae,  also  as  an  accessory  muscle  of  inspiration  by 
raising  and  fixing  the  second  rib. 

The  Common  Carotid  Artery.      Figs.  18,  71. 

On  the  right  side  the  common  carotid  extends  from  the 
bifurcation  of  the  innominate  behind  the  sternoclavicular 
articulation,  upward  to  the  level  of  the  upper  border  of  the 
thyroid  cartilage,  where  it  divides  into  the  external  and 
internal  carotids. 

On  the  left  side  the  artery  arises  as  the  middle  branch 
from  the  arch  of  the  aorta.  Its  course  is  upward  to  the 
same  point  as  on  the  right  side. 

Relations. — The  relations  of  the  thoracic  portion  of  the 
left  common  carotid  are  given  on  page  340. 

In  the  neck  they  are  alike. 

At  the  base  of  the  neck  the  common  carotids  are  about 
an  inch  apart,  at  their  termination  about  two  inches  apart. 

The  course  of  the  artery  is  indicated  by  the  anterior  bor- 
der of  the  sternomastoid  (natural  landmark),  or  a  line 
drawn  from  the  sternoclav^icular  articulation  to  the  front  of 
the  mastoid  process  (artificial). 

The  common  carotid,  internal  jugular,  and  pneumogas- 
tric  nerve  are  contained  within  the  same  sheath  of  the  deep 


102  A  MANUAL  OF  ANATOMY. 

cervical  fascia,  yet  each  is  separated  from  the  other  by  a 
partition  of  the  same.  The  artery  is  internal,  the  vein  ex- 
ternal, and  the  nerve  between  and  behind  them  both. 

Superficially  or  externally  :  Skin,  platysma,  anterior  layer 
of  deep  cervical  fascia. 

It  is  overlapped  by  the  sternomastoid  behind,  and  by 
the  thyroid  gland  in  front,  and  below  is  covered  by  the 
sternomastoid,  sternohyoid,  and  sternothyroid  muscles. 
From  above  downward  the  artery  is  crossed  by  the  supe- 
rior and  middle  thyroid  veins,  the  communicating  vein  from 
the  facial  to  the  anterior  jugular,  the  sternomastoid  artery 
(from  the  superior  thyroid),  the  descendens  hypoglossi 
(which  courses  downward  and  forward  upon  the  sheath  of 
the  artery  and  is  joined  by  the  communicantes  hypoglossi), 
the  omohyoid  muscle  (dividing  the  artery  into  two  por- 
tions, see  page  79),  and  the  anterior  jugular  vein  (as  it 
turns  backward  to  empty  into  the  external  jugular,  see 
page  74). 

At  the  inner  side  :  The  trachea,  oesophagus  (and  between 
them),  the  recurrent  laryngeal  nerve,  the  thyroid  gland,  cri- 
coid and  thyroid  cartilages,  the  lower  part  of  the  pharynx, 
the  superior  laryngeal  nerve,  branches  of  the  superior  and 
inferior  thyroid  arteries,  and  the  veins  of  the  same. 

At  the  outer  side  :  The  internal  jugular  vein,  pneu- 
mogastric  nerve  (between  and  behind  both  artery  and 
vein). 

Centrally  ;  Longus  colli,  rectus  anticus  major  muscles, 
pneumogastric  (see  above),  sympathetic  and  its  cardiac 
branches,  inferior  thyroid  artery,  and  recurrent  laryngeal 
nerve. 

Above  :  In  the  angle  of  bifurcation  Hes  the  carotid  gland, 
a  structure  composed  of  fine  capillaries  invested  with  con- 
nective tissue.      It  is  not  a  lymphatic  gland. 


THE  NECK,  ANTERIOR.  103 

The  Pneumogastric  Nerve.     Figs.  lo,  ii,  17,  18. 

This  leaves  the  interior  of  the  skull  through  the  jugular 
foramen,  lying  in  the  central  compartment  of  the  same  with 
the  ninth  and  eleventh  nerves,  passes  straight  downward 
behind  and  between  the  internal  jugular  vein  and  the  inter- 
nal carotid  artery,  then  between  the  same  vein  and  the 
common  carotid,  resting  upon  the  fascia  covering  the  rec- 
tus capitis  anticus  major,  and  longus  colli  muscles. 

At  the  base  of  the  neck  the  right  nerve  crosses  over  the 
front  of  the  subclavian  artery  and  lies  between  it  and  the 
innominate  vein. 

On  the  left  side  it  lies  between  and  behind  the  subclavian 
and  common  carotid  arteries. 

For  its  course  and  relations  in  the  chest  see  page  342. 

Just  below  the  skull  will  be  found  the  enlargement  of  the 
pneumogastric  called  the  ganglion  of  the  trunk.  To  this 
the  hypoglossal  nerv^e  is  firmly  united  by  connective  tissue. 

Brandies  of  the  Pneumogastric. — The  pneumogastric  re- 
ceives branches  from  the  spinal  accessor^%  hypoglossal, 
superior  cervical  sympathetic  ganglion,  and  the  loop  be- 
tween the  two  upper  cervical  nerves.  These  branches 
enter  the  ganglion  of  the  trunk. 

The  pneumogastric  gives  off  minute  branches  to  the 
glossopharyngeal,  spinal  accessory,  hypoglossal,  and  two 
upper  cervical  nerves. 

The  branches  of  distribution,  in  the  neck. 

(a)  ^\\Q.  pharyngeal :  May  be  one  or  more  ;  come  origi- 
nally from  the  spinal  accessory  branch  of  communication. 
They  form,  with  branches  from  the  sympathetic  and  glosso- 
pharyngeal, the  pharyngeal  plexus,  from  which  branches 
are  given  to  the  muscles  and  mucous  membrane  of  the 
pharynx. 

{U)  The  superior  laryngeal :  Arises  from  the  lower  part 


104  A  MANUAL  OF  ANATOMY. 

of  the  ganglion  of  the  trunk,  passes  downward  and  forward 
under  both  external  and  internal  carotids  to  the  side  of  the 
larynx,  where  it  divides  into  two  branches. 

The  superior,  larger,  internal,  or  sensory  branch  enters 
the  larynx  through  the  thyrohyoid  membrane  with  the 
laryngeal  branch  of  the  superior  thyroid  artery  and  sup- 
plies sensation  to  the  mucous  membrane  of  the  interior  of 
the  larynx.  It  communicates  with  the  inferior  laryngeal 
nerve. 

The  inferior,  smaller,  external,  or  motor  branch  descends 
to  terminate  in  the  cricothyroid  muscle,  which  it  suppHes. 

From  this  branch  are  some  fine  filaments  of  communica- 
tion to  the  sympathetic  and  pharyngeal  plexus. 

ic)  The  recurrent  laryngeal  or  inferior  laryngeal :  The 
right  one  is  given  off  as  the  pneumogastric  turns  over  the 
subclavian  artery,  the  left  as  it  passes  in  front  of  the  arch 
of  the  aorta.     See  page  342. 

In  the  neck  they  both  pass  behind  the  common  carotids 
and  inferior  thyroid  arteries,  then  in  the  groove  between  the 
trachea  and  the  oesophagus,  where  they  are  covered  by  the 
thyroid  gland,  then  under  the  lower  border  of  the  inferior 
constrictor,  where  they  enter  the  interior  of  the  larynx  and 
are  distributed  to  all  the  muscles  of  that  organ  excepting 
the  cricothyroid. 

The  recurrent  nerve  also  furnishes  small  branches  to  the 
trachea,  oesophagus,  inferior  constrictor,  inferior  cervical 
sympathetic  ganglion,  and  the  cardiac  plexus. 

((^)  The  cervical  cardiac  branches.  For  the  Thoracic, 
see  page  354. 

There  are  one  or  two  upper  cervical  cardiac  branches 
which  join  the  cardiac  branches  of  the  sympathetic.  See 
page  106. 

There  is  one  lower,  which  comes  off  the  pneumogastric 


Fig.  i8.  Dissection  of  Neck.— [Structures  named  in  preceding  figures  will  not  be 
re-named  in  this,  except  as  necessary  to  clearness.] — i,  Pneumogastric  nerve.  2,  Sympa- 
thetic cord.  3,  Phrenic  nerve.  4,  Ascending  cervical  artery.  5,  Scalenus  anticus  muscle. 
6,  Posterior  scapular  artery.  See  text,  page  113.  7,  Brachial  plexus.  8,  Stylo-glossus 
muscle.  9,  Glosso-pharyngeal  nerve.  10,  Wharton's  duct.  11,  Gustatory  nerve  and 
site  of  the  submaxillary  ganglion.  12,  Genio-hyo-glossus  muscle.  13,  Genio-hyoid  mus- 
cle. 14,  Superior  laryngeal  nerve.  15,  Thyroid  gland.  16,  CEsophagus.  17,  Inferior 
(recurrent)  laryngeal  nerve.  18,  Trachea.  19,  Innominate  artery.  20,  Vertebral  artery. 
21,  Internal  mammary  artery.    22,  Subclavian  vein.    23,  Subclavian  arterj-. 


106  A  MANUAL  OF  ANATOMY. 

as  it  is  entering  the  chest  at  the  root  of  the  neck.  The 
right  nerve  passes  to  the  deep  cardiac  plexus  and  the  left 
to  the  superficial  cardiac  plexus.     See  page  354. 

For  the  remaining  branches  of  the  pneumogastric  nerve 
see  page  342. 

The  Cervical  Sympathetic  Cord  and  G-anglia.    Figs.  12, 

18. 
There  are  three  cervical  ganglia,  the  superior,  middle, 
and  inferior,  joined  by  the  nerve  cord  which  extends  from, 
the  base  of  the  skull  into  the  thorax,  where  it  is  continued 

as  the  thoracic  cord.  The  sympathetic  cord  lies  upon  the 
rectus  capitis  anticus  major  and  the  longus  colli  (separated 
from  them  by  the  prevertebral  fascia),  and  behind  the  inter- 
nal and  common  carotid  arteries.  The  pneumogastric  nerve 
lies  external  to  the  cord. 

The  Superior  Cervical  Ganglion, 

This  is  about  an  inch  in  length  ;  it  lies  in  front  of  the 
transverse  process  of  the  second  and  third  cervical  ver- 
tebrae. 

It  gives  off  the  ascending  branch,  which  passes  upward 
with  the  carotid  artery  and  forms  the  carotid  and  cavernous 
plexuses ;  the  arterial  branches  to  the  external  carotid  and 
its  branches  ;  the  communicating  filaments  to  the  ninth, 
tenth,  and  twelfth  cranial  nerves  ;  pharyngeal  branches  to 
the  pharyngeal  plexus  ;  the  superior  cardiac  nerve,  which  on 
the  right  side  passes  to  the  deep  cardiac  plexus  and  on  the 
left  side  to  the  superficial  cardiac  plexus  (see  page  354); 
and  slender  filaments  to  the  anterior  division  of  the  first 
four  spinal  ner\'es. 

The  middle  cervical  ganglion  is  not  always  constant ; 
when  present  is  found  in  front  of  the  inferior  thyroid  artery 
as  a  slip-ht  thickening  of  the  cervical  cord. 


THE  XECK,  ANTERIOR.  107 

It  furnishes  filaments  to  the  thyroid  gland  and  gives  off 
the  middle  cardiac  nerve,  which  passes  into  the  thorax  to 
end  in  the  deep  cardiac  plexus,  and  is  connected  to  the  fifth 
and  sixth  cervical  nerves. 

The  Inferior  Cervical  Gang-lion. 

This  ganglion  lies  behind  the  vertebral  artery,  and  be- 
tween the  neck  of  the  first  rib  and  the  transverse  process 
of  the  seventh  cervical  vertebra. 

Its  filaments  extend  to  the  seventh  and  eighth  cerv^ical 
nerves,  to  the  vertebral  artery,  and  by  the  inferior  cardiac 
nerve  to  the  deep  cardiac  plexus. 

DISSECTION. 

Divide  the  internal  carotid  near  its  bifurcation  and  retract  the  two  portions. 

Ligate  the  subclavian  vein  at  the  clavicle  (if  the  axillary  has  already  been 
tied,  then  draw  the  vein  under  the  clavicle)  and  turn  it  inward.  Keep  track 
of  the  thoracic  duct  on  the  left  side. 

Divide  the  scalenus  anticus  over  the  subclavian  artery  and  clean  the  entire 
course  (in  the  neck)  of  the  artery  and  its  branches. 

The  Right  Lymphatic  Duct. 

Recei\'es  the  lymphatics  of  the  right  side  of  the  head 
and  neck,  right  upper  extremity,  right  side  of  the  thorax, 
and  from  the  convex  surface  of  the  liver.  It  is  about  an 
inch  long  and  empties  into  the  angle  between  the  internal 
jugular  and  subclavian  as  they  form  the  right  innominate 
vein. 

The  Thoracic  Duct. — See  Thorax,  page  344. 

The  Subclavian  Artery.     Figs.  17,  18. 

The  subclavian  artery  differs  in  its  origin  on  the  two  sides 
of  the  body.  On  the  right  side  it  is  the  external  branch 
of  bifurcation  of  the  innominate  artery  ;  on  the  left  side, 
arises  as  the  last  branch  from  the  transverse  portion  of  the 
aorta. 


108  A  MANUAL  OF  ANATOMY. 

The  artery  terminates  on  both  sides  of  the  body  at  the 
lower  border  of  the  first  rib,  where  the  name  for  the  arterial 
trunk  becomes  the  axillary. 

The  artery  is  divided  into  three  portions  by  the  scalenus 
anticus  muscle.  The  first  portion,  internal  to  the  muscle  ; 
the  second,  behind,  and  the  third  portion  external  to  the 
muscle. 

The  right  artery  is  three  inches,  the  left  about  four  inches 
in  length. 

Relations. — 

First  Portion  of  the  Left  Subclavian  Artery.  (Inserted 
here  to  complete  the  description  of  the  artery.) 

In  front :  Sternohyoid,  sternothyroid,  and  sternomastoid 
muscles.  The  left  pleura  and  lung.  The  left  innomi- 
nate vein.  (In  the  neck),  internal  jugular,  vertebral,  and  sub- 
clavian veins.  Phrenic  nerve  (in  the  neck),  cardiac  nerves 
(from  sympathetic).     Thoracic  duct  (root  of  neck). 

Behind  (and  internal)  :  CEsophagus,  thoracic  duct,  sym- 
pathetic and  inferior  ganglion,  longus  colli  muscle,  and  spinal 
column.      Behind  (and  externally)  :  The  lung  and  pleura. 

At  the  right :  Trachea,  recurrent  laryngeal  nerve, 
oesophagus,  and  thoracic  duct. 

At  the  left :   Left  lung  and  pleura. 

Right  Subclavian  Artery,  First  Portion. 

In  front :  Skin,  superficial  fascia,  platysma,  deep  fascia 
(two  layers),  the  clavicular  origins  of  the  sternomastoid, 
sternothyroid,  and  sternohyoid  muscles.  The  subclavian 
vein,  the  beginning  of  the  innominate,  end  of  the  internal 
jugular  and  vertebral  veins.  Pneumogastric  and  phrenic 
nerves,  the  sympathetic  cardiac  branches.  The  artery  is 
surrounded  by  a  loop  of  the  sympathetic,  called  the  ring 
of  Vieussens  (annulus  Vieussens). 

Behind  :  Longus  colli  muscle,  transverse  process  of  the 


THE  NECK,  ANTERIOR.  109 

seventh  cervical  vertebra,  sympathetic  cord,  cardiac  nerves, 
recurrent  laryngeal,  lung,  and  pleura. 

Below  :  Lung  and  pleura,  loop  of  recurrent  laryngeal, 
and  sympathetic  nerves. 

TJlc  Second  Portiou  of  Right  and  Left  Subclavian  Arteries. 

This  lies  behind  the  scalenus  anticus  muscle. 

In  addition  to  the  fasciae,  skin,  and  muscles  above  given 
as  being  in  front  of  the  first  portion  of  the  right  artery, 
there  are  the  scalenus  anticus  muscle  and  the  phrenic  nerve 
(separated  from  the  artery  by  the  scalenus  muscle). 

Behind  :  Apex  of  the  lung  and  pleura.  Scalenus 
medius. 

Below  :   Pleura  and  lung. 

Above  :  The  brachial  plexus. 

Third  Portion  of  the  Subclavian  Artery,  Right  and  Left. 

This  extends  from  the  outer  border  of  the  scalenus  anti- 
cus to  the  lower  border  of  the  first  rib. 

In  front :  The  skin,  layers  of  fascia,  platysma,  clavicular 
nerves,  the  suprascapular  artery  (if  the  arm  be  elevated)  ; 
the  external  jugular  and  subclavian  veins ;  the  supra- 
scapular and  transverse  cervical  form  a  plexus  in  front  of  the 
artery  before  they  empty  into  the  external  jugular  vein. 

The  nerve  to  the  subclavius  muscle. 

Behind  :  Scalenus  medius,  the  lower  or  third  trunk  of 
the  brachial  plexus. 

Below :  The  posterior  of  the  two  grooves  upon  the 
upper  surface  of  the  first  rib. 

Above  :  The  cords  and  the  first  trunk  (see  page  3 1 2) 
of  the  brachial  plexus.  The  posterior  belly  of  the  omo- 
hyoid muscle. 

Branches  of  the  Subclavian  Artery. 

From  the  First  Portion. — Vertebral,  thyroid  axis,  internal 
mammary. 


110  A  MANUAL  OF  ANATOMY. 

Second  Portion. — Superior  intercostal. 
Third  Portion. — Posterior    scapular    (more    often    than 
from  the  transverse  cervical). 

The  Vertebral  Artery,      Figs,  lO,  i8,  20,  22. 

This  is  the  first  branch  of  the  subclavian.  It  arises 
from  the  upper  and  back  part  of  the  artery,  nea4-  the  inner 
edge  of  the  scalenus  anticus,  passes  vertically  upward  to 
enter  the  foramen  in  the  transverse  process  of  the  sixth 
cervical  vertebra. 

The  artery  continues  upward  through  all  the  foramina 
in  the  vertebrae  above.  On  reaching  the  atlas  it  winds 
backward  around  the  superior  articular  process,  grooving 
the  upper  surface  of  the  posterior  arch,  passes  through 
a  gap  in  the  posterior  occipito-atlantal  ligament,  winds 
forward  and  unites  with  the  opposite  vertebral  at  the 
anterior  margin  of  the  foramen  magnum  to  form  the 
basilar  artery.     Seepage  158, 

For  the  relations  of  the  artery  in  the  suboccipital 
triangle,  see  page  132. 

The  artery  is  divided  into  the  cervical,  vertebral,  occip- 
ital (see  page  132),  and  intracranial  portions. 

The  cervical  portion  is  the  part  of  the  artery  before 
it  enters  the  vertebral  foramen.  It  lies  in  the  interval 
between  the  longus  colli  and  scalenus  anticus  muscles, 
and  upon  the  transverse  process  of  the  seventh  cervical 
vertebra  and  sympathetic  nerve.  In  front  of  it  are  the 
vertebral  and  internal  jugular  veins,  the  inferior  thyroid 
artery,  and,  on  the  left  side,  the  thoracic  duct  crosses  it 
from  within  outward. 

The  vertebral  portion  is  that  part  of  the  artery  in  transit 
through  the  vertebral  foramina,  where  it  is  surrounded  by 
a  venous  plexus  and  sympathetic  filaments. 


THE  NECK,  ANTERIOR.  Ill 

The  second  portion  gives  off  the  lateral  spinal  and  mus- 
cular branches  to  the  contents  of  the  spinal  canal  and 
external  spinal  muscles. 

The  Vertebral  Vein. 

Begins  in  a  plexus  of  small  veins  in  the  suboccipital 
triangle,  where  it  communicates  with  the  intraspinal,  deep 
cervical,  and  occipital  veins.  It  retraces  the  course  of  the 
artery  through  the  vertebral  foramina,  forming  a  venous 
plexus  about  it  in  its  course,  appears  at  the  foramen  in  the 
sixth  cervical  vertebra,  passes  across  the  vertebral  and 
subclavian  arteries,  and  opens  into  the  innominate  vein. 

Near  its  termination  it  is  joined  by  the  deep  cervical 
vein.      See  page  136. 

The  Th3n'oid  Axis.       Fig.  1 8. 

This  is  a  short  trunk  from  the  upper  and  front  portion 
of  the  first  portion  of  the  subclavian,  at  the  inner  border 
of  the  scalenus  anticus  muscle. 

It  breaks  up  into  the  inferior  thyroid,  transverse  cervi- 
cal, and  suprascapular  arteries. 

The  Inferior  Thyroid.      Fig.  18. 

This  is  the  largest  branch  of  the  axis.  It  takes  a 
winding  course  upward  and  inward  to  the  lower  border 
of  the  thyroid  gland. 

In  its  course  it  passes  in  front  of  the  vertebral  artery, 
longus  colli  muscle,  and  the  recurrent  laryngeal  nerve ; 
and  behind  the  internal  jugular  vein,  pneumogastric  nerve, 
common  carotid  artery,  sympathetic  nerve  cord  and  its 
middle  cervical  ganglion  (when  that  is  present). 

Its  branches  are  {a)  muscular,  to  the  adjacent  muscles. 
{F)  Ascenditig  cervical,  which  runs  upward  bet\\een  the 
vertebral  attachments  of  the  scalenus  anticus  and  rectus 
capitis  anticus  major,  following  up  the  phrenic  nerve,  sup- 


112  A  MANUAL   OF  ANATOMY. 

plying  the  deep  muscles  of  the  neck,  and  some  branches  to 
the  interior  of  the  spinal  canal,  (c)  Tracheal,  to  the  trachea. 
{(T)  CEsophageal,  to  the  oesophagus.  {e)  The  inferior 
laryngeal,  which  accompanies  the  inferior  laryngeal  nerve 
into  the  larynx. 

The  Transverse  Cervical  Artery.      Figs.  17  and  18. 

It  is  the  second  (usually)  in  size  of  the  branches  of  the 
thyroid  axis. 

Its  course  is  as  indicated  by  its  name,  transversely  out- 
ward across  the  neck  just  above  the  clavicle,  to  disappear 
under  the  trapezius  muscle,  where  it  divides  into  its  termi- 
nal branches. 

In  its  outward  course  it  crosses  the  phrenic  nerve,  scale- 
nus anticus,  brachial  plexus,  and  scalenus  medius ;  and  is 
crossed  by  the  omohyoid  (posterior  belly). 

Its  terminal  branches  are  the  {a)  siipej^ficial  cervical, 
which  turns  upward  under  the  trapezius  to  anastomose  with 
the  superficial  branch  of  the  princeps  cervicis  of  the  occipi- 
tal artery,  in  its  course  giving  branches  to  the  trapezius, 
levator  anguli  scapulae  and  splenius  muscles,  between  which 
it  lies  ;  and  (1!^)  the  posterior  scapular,  which  is  usually  given 
off  the  third  portion  of  the  subclavian. 

If  given  off  the  transverse  cervical  its  course  is  downward 
and  backward  under  the  levator  anguli  scapulae  to  the  upper 
angle  of  the  scapula. 

For  the  continuation  of  its  course,  see  page  370. 

The  Suprascapular  Artery.     Fig.  18. 

The  third  and  often  smallest  branch  of  the  thyroid  axis. 

It  takes  a  course  outward  behind  the  clavicle  to  the 
suprascapular  notch,  where  it  crosses  above  the  ligament, 
which  converts  this  notch  into  a  foramen,  the  nerve  of 
this  name /«.f.ym^  through  \he  foramen.     See  page  371. 


THE  XECK,  ANTERIOR.  113 

The  artery  crosses  the  phrenic  nerve,  scalenus  anticus 
muscle,  subclavian  artery,  and  brachial  plexus. 

Its  branches  in  this  part  of  its  course  are  {li)  muscular  to 
the  sternomastoid  and  subclavius ;  {li)  nutrient  to  the 
clavicle  ;  {c)  the  suprasternal ;  {d)  supra-acromial  to  these 
regions  ;  and  {c)  the  articular  to  the  acromioclavicular  and 
shoulder  joints.    For  the  remaining  branches,  see  page  371. 

The  Internal  Mammary  Artery.      Fig.  18. 

It  is  given  off  close  to  the  scalenus  anticus  muscle  from 
the  under  surface  of  the  subclavian.  It  descends  directly 
into  the  thorax  behind  the  cartilage  of  the  first  rib.  For 
its  course,  relations,  branches,  and  veins,  see  pages  320. 

The    Superior   Intercostal  Artery. — Second   Portion    of 
the  Subclavian.      Fig.  74. 

This  branch  arises  from  the  back  of  the  subclavian,  be- 
hind the  inner  border  of  the  scalenus  anticus  muscle. 

It  takes  an  arched  course  backward,  upward,  and  then 
downward  into  the  chest,  passing  in  front  of  the  neck  of  the 
first  rib. 

From  the  back  of  the  arch  it  gives  off  the  deep  cervical 
(profunda  cervicis)  branch,  which  passes  backward  between 
the  transverse  process  of  the  seventh  cervical  vertebra  and 
the  neck  of  the  first  rib  to  the  back  of  the  neck,  where  it 
will  be  found  between  the  complexus  and  semispinalis  colli 
muscles.     Seepage  135. 

For  the  costal  portion  of  the  superior  intercostal,  see 
page  346. 

The  Posterior  Scapular. — The  Third  Portion  of  the  Sub- 
clavian.     Figs.  17,  18. 

The  posterior  scapular  artery  usually  arises  from  this 
portion  of  the  subclavian.  When  arising  as  a  branch  of  the 
subclavian  the  posterior  scapular  takes  a  course  backward 


114  A  MANUAL   OF  ANATOMY. 

between  the  lower  trunks  of  the  brachial  plexus,  to  reach 
a  position  under  the  levator  anguli  scapulae  muscle  ;  from 
here  on  its  course  is  as  described  on  page  370. 

The  Thyroid  Qland.      Fig.  18. 

The  thyroid  gland  is  a  ductless  gland,  composed  of  two 
symmetrical  halves,  which  are  joined  by  a  narrow  isthmus. 

The  halves,  or  lobes,  of  the  gland  rest  upon  the  antero- 
external  surface  of  the  trachea,  and  the  isthmus  crosses  its 
front. 

Each  lobe  is  about  two  inches  long,  and  one  and  one- 
half  inches  broad,  and  three-fourths  of  an  inch  thick.  The 
lower  end  of  the  lobe  is  broader  than  its  upper  end.  Its 
antero-external  surface  is  convex,  and  its  inner  surface 
adapted  to  the  trachea,  against  which  it  rests. 

It  reaches  from  the  fifth  or  sixth  tracheal  ring  upward  to 
cover  the  lower  fourth  of  the  thyroid  cartilage. 

The  isthmus  is  about  one-half  an  inch  wide  and  crosses 
the  second  and  third  tracheal  rings. 

The  entire  gland  weighs  from  one  to  two  ounces,  and  is 
usually  heavier  in  females  than  males. 

Relations. — In  front :  The  integument,  platysma,  small 
part  of  the  sternomastoid,  deep  fascia  (two  layers),  omo- 
hyoid, sternohyoid,  and  sternothryoid. 

Laterally  :  The  sheath  of  the  common  carotid,  internal 
jugular,  and  pneumogastric.  The  superior  and  inferior 
thyroid  arteries. 

Internally  :  The  larynx  and  trachea,  recurrent  laryngeal 
nerves. 

Posteriorly :  Pharynx,  and  on  the  left  side  the  oeso- 
phagus. 

The  arteries  of  the  gland  :  The  superior  thyroid  from  the 
external  carotid,  the  inferior  thyroid  from  the  thyroid  axis, 


THE  NECK,  ANTERIOR.  115 

and  sometimes  the  tkyroidea  inia  from  the  arch  of  the  aorta 
or  the  innominate  artery. 

Veins  :  Superior,  middle,  and  inferior  thyroid  ;  the  first 
two  empty  into  the  internal  jugular,  the  last  two  into  the 
innominate. 

Nerves  :  From  the  middle  and   inferior  cervical  ganglia. 

Lymphatics  :  Pass  to  the  right  lymphatic  and  the  tho- 
racic ducts. 

Muscles  :  The  thyroid  gland  is  at  times  found  to  be 
connected  to  the  hyoid  bone  by  a  detached  slip  of  the 
thyrohyoid  muscle,  which  is  called  the  levator  glandulae 
thyroideae. 

Ligaments  :  The  gland  is  retained  in  its  position  against 
the  trachea  and  larynx  by  the  third  layer  of  cervical  fascia 
(see  page  139),  which  forms  a  capsule  for  the  gland  and 
encloses  all  these  structures. 

The  student  should  prepare  himself  upon  the  trachea, 
thoracic  duct,  and  brachial  plexus.  The  description  of 
these  structures  is  omitted  here,  but  is  given,  trachea,  p. 
356  ;  thoracic  duct,  p.  344,  and  brachial  plexus,  p.  312. 


DISSECTION  OF  THE  DEEP  FACE  AND  PHARYNX. 

The  plan  of  dissection  is  determined  by  whether  the  skull  is  to  be  pre- 
served for  future  use  or  not.  If  it  is  desirable  to  save  the  skull  intact,  the  first 
plan  can  be  adhered  to,  if  otherwise,  the  second. 

The  first  plan  : — 

Sever  the  attachment  of  the  masseter  muscle  close  to  the  zygomatic  arch, 
draw  it  downward  and  carefully  cut  it  away  from  its  insertion.  In  doing 
this  recognize  and  save  the  masseteric  nerve  and  artery,  which  reach  the  muscle 
through  the  sigmoid  notch  in  the  lower  jaw.  Then  remove  the  masseter 
entirely. 

Cut  the  temporal  muscle  from  its  insertion  into  the  coronoid  process,  keep- 
ing close  to  the  bone.  When  the  insertion  is  cut  through,  draw  the  tendon 
upward  through  the  zygomatic  arch,  sever  the  muscular  attachment  to  the 
temporal  fossa,  saving  the  deep  temporal  nerves  and  arteries,  and  remove  the 
muscle  entirely.      (In  the  preceding  plan  the  skull-cap  has  not  been  removed.) 


116  A  MANUAL   OF  ANATOMY. 

Expose  the  external  lateral  ligament  of  the  lower  jaw,  then  divide  it,  and 
continue  the  disarticulation  of  the  lower  jaw. 

Sever  the  attachment  of  the  internal  pterygoid  muscle  and  the  stylomaxil- 
lary  ligament  close  to  the  jaw.  Work  carefully  forward  until  the  dental 
foramen  is  reached,  then  sever  the  internal  lateral  ligament.  This  releases 
the  lower  jaw  sufficiently  to  permit  its  being  drawn  forward  and  downward. 

Expose  the  inferior  dental  nerve  and  artery  and  cut  them  close  to  the  dental 
foramen.     Save  the  mylohyoid  nerve. 

Trace  the  auriculo- temporal  nerve,  from  where  it  was  found  posterior  to  the 
temporal  artery,  around  the  temporomaxillary  articulation  to  its  origin  by  two 
branches  from  the  inferior  maxillary  nerve. 

Clean  the  branches  of  the  first  portion  of  the  internal  maxillary  artery,  viz.  : 
deep  auricular,  tympanic,  middle  meningeal,  small  meningeal,  inferior  dental ; 
and  of  the  second  portion,  viz.  :  masseteric,  deep  temporal,  buccal,  and  the 
buccal. 

All  of  these  will  be  found  with  care,  excepting,  perhaps,  the  first  two. 

Clean  the  pterygoid  muscles  as  far  as  possible  at  this  stage. 

Divide  the  external  pterygoid  close  to  its  insertion  into  the  front  of  the  neck 
of  the  jaw,  cut  away  the  buccinator  from  the  lower  jaw,  and  draw  the  jaw 
still  farther  downward  and  forward. 

Trace  the  inferior  maxillary  nerve  up  to  the  foramen  ovale,  and  its  inferior 
dental  (has  been  divided),  mylohyoid,  lingual,  and  buccal  branches. 

Cut  away  the  external  pterygoid,  follow  the  internal  maxillary  artery  to  the 
sphenomaxillary  fossa.  Draw  the  jaw  upward,  complete  the  stylopharyngeus 
muscle,  facial  nerve,  the  occipital  artery,  to  where  it  passes  between  the  rectus 
lateralis  and  the  origin  of  the  posterior  belly  of  the  digastric,  the  spinal 
accessory,  glossopharyngeal,  pneumogastric,  sympathetic,  and  hypoglossal 
nerves.  Find  the  branch  from  the  loop  between  the  first  and  second  cervical 
nerves  to  the  last  nerve. 

Divide  the   stylopharyngeus,  styloglossal  muscles,  the  hypoglossal  nerve. 

Trace  upward  the  ascending  pharyngeal  and  internal  carotid  arteries  to  the 
carotid  canal. 

Cut  the  mylohyoid  muscle,  anterior  belly  of  the  diagastric,  and  the  genial 
muscles  close  to  the  lower  jaw,  and  remove  it  entirely.  Fasten  the  tongue 
forward  with  a  chain  hook. 

The  second  plan  is  intended  to  give  more  room  for  the  dissection,  and  thus 
render  it  somewhat  easier. 

It  contemplates  the  division  of  the  zygomatic  arch  at  both  ends  and  its 
removal,  the  division  of  the  lower  jaw  at  the  symphysis  with  a  saw,  and  the 
separation  of  its  halves. 

The  jaw  can  be  divided  in  the  first  plan  if  the  student  so  desires. 

The  dissection  of  the  parts  then  takes  place  as  outlined  above. 

The  student  should  remember  that  the  dissection  of  small  spaces  where  im- 


THE  XECK,  ANTERIOR.  117 

portant  organs  are  crowded  together  can  be  indicated  in  only  the  most  general 
terms,  and  that  he  must  rely  upon  his  own  judgment,  guided  by  his  previous 
study  of  the  text-book,  plates,  and  the  directions  given. 

The  Inferior  Maxillary  Nerve.      Figs.  1 1,  12. 

This  is  the  third  or  lowest  branch  of  the  fifth  cranial 
nerve.     It  issues  from  the  skull  through  the  foramen  ovale. 

It  is  composed  of  the  entire  motor  portion  of  the  fifth 
and  a  part  of  the  sensory  fibres,  which  unite,  after  travers- 
ing the  foramen  ovale,  to  form  a  single  trunk  that  at  once 
divides  into  a  smaller  anterior  and  a  larger  posterior 
division.  The  anterior  branch  is  mostly  motor,  and  the 
posterior  sensory. 

From  the  trunk  before  its  division  a  filament,  the  recur- 
rent nerve,  passes  into  the  skull  through  the  foramen 
spinosum  with  the  middle  meningeal  artery  ;  and  a  muscu- 
lar branch  to  the  internal  pterygoid,  which  enters  the 
deep  surface  of  the  muscle. 

Branches  of  the  Anterior  Division. 

(i)  The  deep  temporal  nerves.  Usually  two  in  number, 
anterior  and  posterior,  enter  the  deep  surface  of  the  tem- 
poral muscle.  (2)  The  masseteric.  Passes  through  the 
sigmoid  notch  with  the  masseteric  branch  of  the  internal 
maxillary  artery  and  terminates  in  the  masseter  muscle. 
(3)  The  external  pterygoid  nerve  to  that  muscle.  (4) 
The  buccal  nerve  comes  forward  between  the  two  heads 
of  the  external  pterygoid  muscle,  appears  in  the  face  issu- 
ing from  under  the  anterior  border  of  the  ramus  of  the 
jaw  and  lying  upon  the  buccinator  muscle.  The  nerve 
is  distributed  to  the  skin  and  mucous  membrane  of  the 
cheek. 

Brandies  of  the  Posterior  Division. 

(i)  The  auriculo-temporal  nerve.      See  page  26. 

(2)  The  inferior  dental  nerve.   This  is  the  largest  branch 


118  A  MANUAL  OF  ANATOMY. 

of  the  posterior  division.  It  descends  behind  (usually  in- 
ternal to)  the  external  pterygoid  muscle,  passes  between 
the  internal  lateral  ligament  and  ramus  of  the  lower  jaw, 
gives  off  its  mylohyoid  branch,  and  enters  the  inferior 
dental  foramen.  Its  course  is  then  through  the  inferior 
dental  canal,  supplying  branches  to  the  bone  and  teeth, 
until  the  mental  foramen  is  reached,  when  it  comes  for- 
ward through  it  and  terminates  in  the  muscles  and  integu- 
ment of  the  front  of  the  chin  and  the  mucous  membrane 
and  skin  of  the  lower  lip.  The  inferior  dental  nerve  has 
the  inferior  dental  branch  of  the  internal  maxillary  artery 
accompanying  it  in  its  course. 

The  mylohyoid  nerve  passes  downward  and  for- 
ward, grooving  the  inner  surface  of  the  lower  jaw  and 
lying  upon  (beneath)  the  mylohyoid  muscle,  to  which  it 
gives  branches,  and  terminates  in  the  anterior  belly  of  the 
digastric  muscle.     See  page  8i. 

It  is  accompanied  in  the  latter  part  of  its  course  by  the 
submental  branch  of  the  facial  artery. 

(3)  The  lingual  or  gustatory  nerve.  Next  in  size  to 
the  inferior  dental.  Its  course  is  the  same  as  the  inferior 
dental,  lying  internal  to  and  in  front  of  it,  until  the  inferior 
dental  foramen  is  reached.  Here  the  lingual  nerve  con- 
tinues forward  between  the  internal  pterygoid  muscle 
and  the  ramus  of  the  lower  jaw,  then  upon  the  mylo- 
hyoid muscle  close  to  its  origin,  then  between  the  mylo- 
hyoid and  hyoglossus  above  the  deep  portion  of  the 
submaxillary  gland  (see  page  86).  It  joins  Wharton's 
duct  on  its  lower  side  and  passes  with  it  to  the  tip  of 
the  tongue. 

Near  its  origin  the  lingual  nerve  is  joined  by  the  chorda 
tympani,  and  below  the  external  pterygoid  muscle  is 
connected  to  the  inferior  dental  nerve  by  a  small  branch. 


THE  NECK,  AXTERIOR.  119 

It  furnishes   filaments   to   the   submaxillary  ganglion  and 
hypoglossal  nerve  (at  its  terminus). 

The  lingual  supplies  the  mucous  membrane  of  the  side 
of  the  tongue  and  the  floor  of  the  mouth,  and  the  sub- 
lingual gland. 

The  Otic  Gang-lion. 

This  small  ganglion  (one-sixth  of  an  inch  in  longest 
dimension)  lies  internal  to  the  inferior  dental  nerve,  in 
front  of  the  middle  meningeal  artery,  and  close  under  the 
foramen  ovale. 

Its  roots  are  sensory  (and  motor),  from  inferior  maxillary 
(through  the  internal  pterj^goid)  nerve  ;  motor,  from  the 
small  (lesser)  petrosal  nerve  (which  brings  fibres  from  the 
seventh  and  ninth  nerves);  and  sympathetic,  from  the  plexus 
on  the  middle  meningeal  artery.  Its  branches  of  distribu- 
tion are  supplied  to  the  tensor  palati  and  tensor  tympani 
muscles,  to  the  parotid  gland  (by  way  of  the  auriculotem- 
poral nerve  with  which  these  filaments  pass),  and  to  the 
chorda  tympani. 

The  Submaxillary  Ganglion.      Fig.  i8. 

The  submaxillary  ganglion  lies  between  the  lingual 
nerve,  Wharton's  duct,  and  the  anterior  portion  of  the  sub- 
maxillary gland.  It  is  about  the  size  of  the  head  of  a 
common  pin.  It  receives  its  motor  root  from  the  chorda 
tympani,  the  sensory  root  from  the  lingual,  the  sympa- 
thetic from  the  plexus  upon  the  facial  artery.  Its  fila- 
ments are  distributed  to  the  submaxillary  gland,  Wharton's 
duct,  and  filaments  to  the  lingual  nerve  which  pass  on  to 
the  sublingual  gland  and  the  tongue. 

The  Sublingual  Gland. 

This  is  the  smallest  of  the  salivary  glands.  It  lies 
immediately  under  the   mucous   membrane   of  the  mouth, 


120  A  MANUAL   OF  ANATOMY. 

and  in  the  sublingual  fossa  of  the  inferior  maxilla.  It 
rests  upon  the  mylohyoid  muscle,  and  has  the  geniohyo- 
glossus  muscle  and  the  opposite  gland  at  the  inner  side. 
Behind,  it  comes  in  contact  with  the  deep  lobe  of  the  sub- 
maxillary gland. 

Its  main  duct  is  called  the  duct  of  Rivinus.  It  accom- 
panies Wharton's  duct  and  opens  with  it  upon  the  top  of 
the  same  papilla  in  the  mouth. 

Numerous  smaller  ducts  from  the  anterior  portion  of 
the  gland  open  upon  the  floor  of  the  mouth. 

The  blood  supply  is  from  the  sublingual  (from  the  lin- 
gual) and  the  submental  (from   the  facial). 

The  nerve  supply  is  from  the  gustatory  (lingual)  and 
sympathetic. 

The  Internal  Maxillary  Artery, 

The  internal  maxillary  artery  is  the  larger  branch  of 
bifurcation  of  the  external  carotid.  It  is  given  off  behind 
the  neck  of  the  lower  jaw  within  the  parotid  gland. 

It  follows  a  tortuous  course  forward  and  inward,  passing 
between  the  neck  of  the  jaw  and  the  internal  lateral 
ligament,  then  upward  and  forward  across  the  front  (exter- 
nal surface)  of  the  external  pteryoid  muscle,  then  turns 
into  the  sphenomaxillary  fossa,  where  it  divides  into  its 
terminal  branches.  The  course  of  the  artery  divides  it 
into  three  portions,  the  maxillary,  behind  the  neck  of  the 
jaw  ;  the  pterygoid,  in  connection  with  the  pterygoid 
muscle  ;  and  the  sphenomaxillary,  within  this  fossa. 

BraiicJies  of  the  Inteinial  Maxillary. — Maxillary  portion 
or  first  portion. 

(i)  The  deep  auricular.  A  small  branch  to  the  anterior 
wall  of  the  external  meatus. 

(2)  The  tympanic  branch,  a  very  slender  artery  which 


THE  NECK,  ANTERIOR.  121 

passes   upward  to  the   Glaserian   fissure,  and  through  this 
to  the  tympanum. 

(3)  The  middle  meningeal.  The  largest  and  most  im- 
portant branch  of  the  internal  maxillary  artery.  It  arises 
from  the  upper  surface  of  the  artery,  in  its  situation  between 
the  neck  of  the  jaw  and  the  internal  lateral  ligament,  runs 
upward  behind  the  external  pterygoid  muscle,  then  between 
the  two  roots  of  the  auriculotemporal  nerve,  and  enters  the 
foramen  spinosum  in  the  sphenoid  bone.  For  the  course 
of  the  artery  within  the  skull,  see  page  44. 

(4)  The  small  meningeal.  Often  a  branch  from  the 
middle.  Follows  upward  the  inferior  dental  nerve  and  dis- 
appears through  the  foramen  ovale.  It  supplies  the  Gas- 
serian  ganglion,  the  cavernous  sinus,  and  the  adjacent  dura. 

(5)  The  inferior  dental  artery.  This  accompanies  the 
nerve  of  the  same  name  in  its  course  through  the  inferior 
dental  canal,  and  appears  through  the  mental  foramen  as 
the  mental  artery. 

Before  it  enters  the  inferior  dental  canal  the  artery  gives 
off  a  branch  (Ungual)  which  follows  the  lingual  nerve,  and 
another  (the  mylohyoid)  which  runs  forward  with  the  mylo- 
hyoid nerve. 

Pterygoid,  or  second  portion  : — 

(i)  The  masseteric.  Reaches  the  deep  surface  of  the 
masseter  muscle  through  the  sigmoid  notch  of  the  jaw, 
and  in  company  with  the  corresponding  nerve  to  the 
muscle. 

(2)  The  deep  temporal,  anterior  and  posterior,  are  dis- 
tributed to  the  under  surface  of  the  temporal  muscle.  They 
and  the  deep  temporal  nerves  will  be  found  together. 

(3)  The  buccal.  Follows  the  buccal  nerve  downward  and 
forward  to  supply  the  buccinator  muscle  and  the  skin  and 
mucous  membrane  of  the  cheek. 


122  A  MANUAL  OF  ANATOMY. 

The  sphenomaxillary,  or  third  portion  : — 
(i)  Branches  which  supply  the  molar  and  bicuspid  teeth, 
mucous  membrane  of  the  antrum,  and  twigs  to  the  gums, 
given  off  from  the  internal  maxillary  upon  the  back  of  the 
superior  maxilla. 

(2)  The  infra-orbital.  This  runs  forward  with  the  superior 
maxillary  nerve  through  the  infra-orbital  canal,  and  appears 
upon  the  face  through  the  infra-orbital  foramen,  where  it 
breaks  up  into  branches  to  the  surrounding  muscles  and  in- 
tegument of  the  upper  lip,  lower  eye-lid,  and  to  the  lachry- 
mal sac. 

Within  the  canal  it  supplies  orbital  branches  to  inferior 
obHque  and  rectus  muscles  ;  the  anterior  dental,  to  the 
canine  and  incisive  teeth  and  mucous  membrane  of  the 
antrum  ;  and  the  nasal  branch  to  the  mucous  membrane  of 
the  nose. 

(3)  The  superior  palatine  artery.  Its  course  is  down 
through  the  posterior  palatine  canal,  along  the  roof  of  the 
mouth,  and  up  through  Stenson's  foramen  into  the  nose 
to  anastomose  with  the  nasopalatine  artery.  It  supplies 
the  soft  palate,  tonsils,  and  mucous  membrane  of  the 
mouth. 

(4)  The  Vidian  artery.  Runs  backward  through  the 
Vidian  canal,  supplying  the  Eustachian  tube  and  roof  of 
pharynx. 

(5)  The  pterygopalatine.  A  twig  through  the  pterygo- 
palatine canal  to  the  roof  of  the  pharynx. 

(6)  The  nasal,  or  nasopalatine.  Passes  through  the 
sphenopalatine  foramen  to  supply  the  ethmoidal  cells, 
frontal  sinus,  and  antrum.  The  continuation  of  the  artery 
extends  forward  and  downward  upon  the  vomer  and  termi- 
nates by  anastomosing  with  the  anterior  terminus  of  the 
superior  palatine  artery,  through  Stenson's  foramen. 


THE  NECK,  ANTERIOR.  123 

The  Stylohyoid  Ligament. 

This  is  the  fibrous  band  or  cord  which  connects  the  tip  of 
the  styloid  process  with  the  lesser  cornu  of  the  hyoid  bone. 
It  serves  to  hold  the  latter  in  position. 

The  Pterygomaxillary  Ligament. 

This  consists  of  the  fibrous  interval  between  the  buccina- 
tor muscle  in  front  and  the  superior  constrictor  muscle 
behind,  and  extends  from  the  tip  of  the  hamular  process  of 
the  internal  pterygoid  plate  to  the  posterior  extremity  of 
the  mylohyoid  ridge. 

The  Stylomaxillary  Ligament. 

This  is  that  portion  of  the  deep  cervical  fascia  which  ex- 
tends from  the  front  of  the  styloid  process  to  the  posterior 
border  of  the  ramus  and  angle  of  the  inferior  maxillary  bone. 
It  separates  the  masseter  muscle  and  parotid  gland  exter- 
nally from  the  internal  pterygoid  muscle  and  submaxillary 
gland  internally. 

Pterygoideus  Bxternus. 

Origin. — Upper  head,  from  the  under  surface  of  the  great 
wing  of  the  sphenoid  bone  between  the  foramen  ovale  and 
spinosum  and  the  pterygoid  ridge. 

The  lower  head,  from  the  outer  surface  of  the  external 
pterygoid  plate. 

Inscj'tion. — Into  the  front  of  the  neck  of  the  condyle  of 
the  lower  jaw,  and  the  interarticular  fibrocartilage  of  the 
temporomaxillary  articulation. 

Nerve  Sitpply. — The  inferior  maxillar>'  nerve. 

Action. — To  draw  the  interarticular  cartilage  and  the  con- 
dyle of  the  jaw  forward  (and  inward).  If  both  muscles  act, 
the  jaw  is  projected  directly  forward  ;  when  one  acts,  the 
jaw  is  turned  to  the  opposite  side  ;  if  they  act  alternately,  the 
jaw  is  moved  from  side  to  side,  as  in  the  grinding  movement. 


124  A  MANUAL   OF  ANATOMY. 

Pterygoideus  Internus.      Fig.  I2. 

Origin. — From  the  pterygoid  fossa,  tuberosities  of  the 
superior  maxillary,  and  palate  bones. 

Insertion. — Into  the  inner  surface  of  the  ramus  and 
angle  of  the  lower  jaw  below  the  inferior  dental  foramen. 

Nerve  Supply. — The  inferior  maxillary. 

Action. — To  close  the  jaw,  to  draw  it  forward,  to  assist 
in  the  grinding  movements. 

DISSECTION. 
Clean  the  constrictor  muscles,  and  remove  the  prevertebral  fascia  from 
the  muscles  it  covers. 

The  Pharynx. 

This  is  a  fibromuscular  cavity  situated  at  the  base  of 
the  skull,  behind  the  nasal  (above)  and  buccal  (below) 
cavities  and  larynx,  and  in  front  of  the  spinal  column. 

Its  length  is  four  and  one-half  inches  from  the  base  of 
the  skull  to  the  level  of  the  cricoid  cartilage  opposite  the 
fifth  cervical  vertebra.  Its  cavity  is  flattened  from  before 
backward,  and  at  its  lower  portion  becomes  obliterated  by 
the  contact  of  its  anterior  and  posterior  walls  (except  dur- 
ing swallowing). 

Into  it  open  the  posterior  nares  (2),  the  Eustachian  tubes 
(2),  the  mouth  (i),  the  larynx  (i),  and  the  oesophagus  (i), 
(total  7).  The  soft  palate  projects  into  it  from  the  front 
and  divides  ^ts  cavity  into  the  nasal  (above)  and  the  buccal 
(below)  portions. 

Its  walls  are  composed  of  mucous  membrane,  fibrous 
tissue  (pharyngeal  aponeurosis),  and  muscles  (the  three 
constrictors,  stylopharyngeus,  and  palatopharyngeus.) 

The  pharynx  is  attached  above,  to  the  base  of  the  skull 
(base  of  sphenoid,  petrous  portion  of  temporal  and  Eus- 
tachian tube,  and  internal  pterygoid  plate)  ;  in  front,  to  the 


THE  KECK,  ANTERIOR.  125 

sides  of  the  posterior  nares,  mouth,  and  larynx  ;  behind,  it 
rests  upon  the  prev^ertebral  fascia  ;  and  below,  is  continued 
into  the  oesophagus.     For  the  Gisopliagiis,  see  Thorax. 

The  Pharyngeal  Plexus. 

This  is  a  loose  meshed  plexus  of  fine  nerve  filaments 
formed  upon  the  outer  surface  of  the  middle  and  inferior 
constrictor  muscles  by  nerve  fibres  from  the  glossopharyn- 
geal, pneumogastric,  and  superior  cervical  ganglion. 

Inferior  Constrictor. 

Origin. — From  the  side  of  the  cricoid  cartilage,  from  the 
inferior  cornu,  the  oblique  line,  and  the  upper  border  of 
the  thyroid  cartilage. 

Liscrtion. — Into  the  fibrous  raphe  of  the  pharynx.  Its 
lower  fibres  pass  horizontally,  the  upper,  obliquely  upward, 
backward,  and  inward. 

The  recurrent  laryngeal  nerve  passes  upward  under  the 
lower  border  of  the  muscle,  and  the  superior  laryngeal  per- 
forates the  thyrohyoid  membrane  above  the  upper  border 
of  the  muscle. 
Middle  Constrictor. 

Origin. — From  both  cornua  of  the  hyoid  bone  and  the 
stylohyoid  ligament. 

Insertion. — Into  the  median  raphe  of  the  pharynx.  Its 
fibres  run  to  the  insertion ;  the  lower,  downward ;  the 
middle,  horizontally  ;  the  upper,  upward.  It  is  overlapped 
below  by  the  inferior  constrictor  and  in  turn  overlaps  the 
superior  above. 

Superior  Constrictor, 

Origin. — From  the  side  of  the  tongue  and  mucous 
membrane,  from  the  posterior  portion  of  the  mylohyoid 
ridge,  the  pterygomaxillary  ligament,  and  the  hamular 
process  and  lower  portion  of  the  internal  pterygoid  plate. 


126  A  MANUAL   OF  ANA  TO  MY. 

Insertion. — Into  the  median  raphe  and  the  pharyngeal 
spine  on  the  basilar  process  of  the  occipital  bone. 

The  stylopharyngeus  muscle  passes  to  its  insertion  be- 
tween the  middle  and  superior  constrictor  muscles. 

The  Sinus  of  Morgagni 

Is  the  semilunar  space  left  between  the  upper  border  of  the 
superior  constrictor  muscle  and  the  base  of  the  skull.  It 
is  covered  by  the  pharyngeal  aponeurosis,  and  through  it 
passes  the  Eustachian  tube  and  levator  palati  muscle. 

Nerve  Supply. — The  three  constrictors  are  supplied  from 
the  pharyngeal  plexus,  the  inferior  in  addition  by  the  recur- 
rent laryngeal. 

Action. — The  constrictors  act  in  rotation  from  above 
downward  in  the  act  of  swallowing.  Their  action  is  in- 
hibited, or  reversed  in  vomiting. 

Rectus  Capitis  Anticus  Major. 

Origin. — From  the  anterior  tubercles  of  the  transverse 
processes  of  the  third  to  sixth  cervical  vertebrae,  inclusive. 

Inso'tion. — Into  the  under  surface  of  the  basilar  process 
of  the  occipital  bone. 

Nerve  Supply. — First  and  second  cervical  nerves. 

Action. — To  flex  the  head. 

Rectus  Capitis  Anticus  Minor. 

Origin. — From  the  base  of  the  transverse  process  of  the 
atlas. 

Insertion. — Into  the  basilar  process  of  the  occipital  bone^ 
behind  the  anticus. 

Nerve  Siipply. — The  first  cervical  nerve. 

ActioJi. — To  flex  the  head. 
Rectus  Capitis  Lateralis. 

Origi^i. — From  the  upper  surface  of  the  transverse  process 
(lateral  mass)  of  the  atlas. 


THE  NECK,  ANTERIOR.  127 

Insertion. — Into  the  jugular  process  of  the  occipital  bone. 
NcT^e  Supply. — First  cervical  nerve. 
Action. — To  flex  the  head  laterally. 

Longus  Colli. 

TJie  vertical  portion. 

Origin. — From  the  sides  of  the  bodies  of  the  sixth  and 
seventh  cervical,  and  the  first,  second,  and  third  dorsal 
vertebrae. 

Insertion. — Into  the  sides  of  the  bodies  of  the  second, 
third,  and  fourth  cervical  vertebrae. 

The  upper  oblique  portion. 

Origin. — From  the  anterior  tubercles  of  the  transverse 
processes  of  the  third,  fourth,  and  fifth  cervical  vertebrae. 

Insertion. — Into  the  tubercle  on  the  anterior  arch  of  the 
atlas. 

The  lower  oblique  portion. 

Origiji. — From  the  sides  of  the  bodies  of  the  first, 
second,  and  third  dorsal  vertebrae. 

Insertion. — Into  the  anterior  tubercles  of  the  transverse 
processes  of  the  fifth  and  sixth  cervical  vertebrae. 

Nerve  Supply. — Filaments  from  the  anterior  divisions  of 
the  cervical  nerves. 

Action. — To  flex  the  neck.  If  one  acts  alone,  to  flex 
the  neck  forward  and  laterally,  and  slightly  rotate  it. 

The  further  dissection  of  the  pharynx  and  the  dissection 
of  the  larynx  and  nasal  fossae  will  be  omitted  until  the  back 
of  the  neck  has  been  completed. 

See  page  141  for  the  directions  and  descriptions. 


128  A  MANUAL   OF  ANATOMY. 

THE  HEAD  AND  NECK,  Posterior. 

Landmarks.     Fig.  76. 

In  the  middle  line  is  the  inion — external  occipital  protu- 
berance ;  outward  from  that  extend  the  superior  curved 
lines  of  the  occipital  bone  to  the  posterior  part  of  the  mas- 
toid processes. 

Along  the  middle  line  of  the  neck  is  a  depression  between 
the  two  muscular  masses,  in  which  can  be  felt  the  spinous 
processes  of  the  cervical  vertebrae,  especially  the  last,  or 
vertebra  prominens.  The  ligamentum  nuchse  lies  also  in 
the  central  depression. 

The  spines  of  the  three  or  four  upper  dorsal  vertebrae 
can  be  felt. 

The  lower  limit  to  the  region  of  the  neck  is  marked  by 
the  spine  of  the  scapula  and  its  acromial  process. 

DISSECTION. 

Incisions. — (i)  Continue  the  median  incision  (over  the  top  of  the  head) 
down  the  back  of  the  neck  to  midway  between  the  shoulders. 

(2)  Make  a  transverse  incision  out  along  the  spine  of  the  scapula  to  the 
point  of  the  shoulder  to  meet  the  similar  anterior  incision.  This  last  incision 
is  the  same  as  number  2,  page  360. 

Remove  the  integument  entirely,  being  careful  not  to  take  off  too  much  of 
the  dense  fascia  which  underlies  it. 

The  Superficial  Fascia  of  the  back  of  the  neck  and 
thorax. 

This  is  a  dense  layer  of  brawny  fascia,  reaching  as  low 
down  as  the  middle  of  the  back,  and  upward  into  the  base 
of  the  head. 

Its  fasciculi  are  very  strong  and  the  interstices  filled  with 
granular  fat.  Inflammation  beneath  this  fascia  produces 
very  marked  effects.  Boils  and  carbuncles  find  their  favorite 
seat  here. 


THE  HEAD  AXD  NECK,  POSTERIOR.  ]29 

The  Deep  Cervical  Fascia. 

This  fascia  is  described  at  page  1 36. 

DISSECTION. 
Remove  the  superficial  and  deep  fascise,  exposing  the  trapezius  muscle,  the 
occipital  artery,  vein,  and  the  cutaneous  nerves,  the  larger  of  which  are  the 
internal  cutaneous  branch  of  the  third  cervical  nerve,  the  great  occipital,  and 
the  small  occipital  (already  found  on  the  dissection  of  the  anterior  of  the  neck, 
see  page  75). 

Trapezius  Muscle,  see  page  362. 

The  Cutaneous  Nerves. 

(i)  The  small  occipital,  described  on  page  90. 

(2)  The  great  occipital.     Figs.   yG  and  yy. 

The  great  occipital  nerve  is  the  internal  branch  of  the 
posterior  division  of  the  second  cervical  nerve.  The  ex- 
ternal branch  of  this  division  is  a  small  nerve  which  sup- 
plies the  inferior  oblique,  complexus,  and  trachelomastoid. 
The  internal  branch  passes  upward  and  inward  and  back- 
ward across  the  lower  border  of  the  inferior  oblique,  then 
through  the  complexus  at  its  middle  and  inner  thirds,  and 
about  one  inch  below  the  superior  line  of  the  occipital  bone, 
then  it  pierces  the  trapezius  close  to  this  curved  ridge  and 
spreads  out  into  branches,  which  accompany  the  branches 
of  the  occipital  artery  and  supply  the  greater  part  of  the 
back  of  the  head.  The  great  occipital  communicates  be- 
neath the  complexus  muscle  with  the  cervical  nerves  above 
and  below,  forming  a  loose  plexus  called  the  posterior  cervi- 
cal plexus  of  Cruveilheir,  and  upon  the  back  of  the  head 
with  the  small  and  third  occipital  nerves. 

(3)  The  third  occipital  nerve.  This  is  the  internal 
branch  of  the  posterior  division  of  the  third  cervical  nerve. 
It  is  much  smaller  than  the  great  occipital,  and  takes  a 
course  below  and  internal  to  that  nerve,  passing  through 
the    complexus    (biventer),    and,    emerging    at    the    inner 

9 


130  A  MAXUAL   OF  ANA  TOMY. 

margin  of  the  trapezius,  supplies  the  integument  over  the 
occipital  protuberance. 

The  remaining  branches  of  the  posterior  divisions  of  the 
occipital  nen"es  are  small.  The  internal  branches  supply 
the  integument  of  the  back  of  the  neck  near  the  middle 
line.  The  external  branches  are  distributed  to  the  muscles 
of  this  region. 

The  Occipital  Artery.     Figs.  76  and  jj. 

It  is  found  at  this  stage  of  the  dissection  as  it  emerges 
from  under  the  inner  border  of  the  splenius  capitis  muscle, 
bet^veen  the  sternomastoid  and  trapezius  muscles  close  to 
the  occipital  bone.  Its  course  is  upward  over  the  back  of 
the  head,  breaking  up  into  branches  as  it  goes,  to  finally 
anastomose  with  the  posterior  temporal,  posterior  auricular, 
and  the  opposite  occipital. 

Its  deeper  course,  from  where  its  dissection  stopped 
(page  95)  as  it  la}'  between  the  rectus  capitis  lateralis  and 
posterior  belly  of  the  digastric,  is  backward  between  those 
muscles  to  the  occipital  groove  on  the  mastoid  process  of 
the  temporal  bone,  then  along  the  insertion  of  the  superior 
oblique  muscle  and  complexus,  being  covered  by  the 
sternomastoid,  splenius  capitis,  trachelomastoid,  and  pos- 
terior belly  of  the  digastric  in  this  part  of  its  course. 

The  arter}'  gives  off  numerous  small  branches  to  the 
muscles,  and  one  of  considerable  size,  the  princeps  cervicis, 
which  courses  downward  beneath  the  splenius  and  com- 
plexus muscles  to  form  an  anastomosis  with  the  profunda 
cervicis.  See  latter,  page  135.  The  preceding  is  usually 
called  the  deep  branch  of  the  princeps  cervicis.  A  small 
branch  of  the  princeps  cervicis  perforates  the  splenius  and 
forms  an  anastomosis  with  the  superficial  cervical  branch 
of  the  transverse  cen'ical.     See  page  1 1 2. 


THE  HEAD  AND  NECK,  POSTERIOR.  131 

Besides  the  muscular  branches,  the  artery  suppHes  the 

integument    of    the    back    of    the    head ;    the    cutaneous 

branches  are  accompanied  by  the  cutaneous  filaments  from 

the  occipital  nerve. 

DISSECTION. 
Divide  the  trapezius  half  an  inch  from  its  attachment  to  the  occipital  bone, 
and  along  the  median  line  (to  meet  the  one  dissecting  it  from  below) ,  and 
turn  the  muscle  downward  and  outward  over  the  shoulder. 

Splenius  Capitis  et  Colli.      Figs.  76  and  jy. 

Origin. — From  the  lower  half  of  the  ligamentum  nuchae, 
the  spinous  processes  of  the  seventh  cervical,  and  five  or 
six  upper  dorsal  vertebrae  and  the  supraspinous  ligament. 

Insertion. — By  two  portions.  The  "capitis"  portion, 
into  the  outer  third  of  the  superior  curved  line  of  the 
occipital  bone  and  the  mastoid  process  of  the  temporal 
bone.  The  "  colli  "  portion,  into  the  posterior  tubercles 
of  the  three  or  four  upper  cervical  vertebrae. 

Nerve  Supply. — The  external  branches  of  the  posterior 
divisions  of  the  cervical  nerves. 

Action. — When    both    act,   they   extend    the    head    and 
neck ;    if  one    acts,    it  rotates   and  flexes    the    head    and 
neck  laterally,  to  the  same  side. 
Levator  Anguli  Scapulae.     See  Upper  Extremity. 
Posterior  Scapular  Artery.     See  page  113. 

DISSECTION. 
Sever  the  splenius  along  its  cranial  and  spinal  attachment  and  turn  the 
muscle  inward. 

Trachelomastoid. 

Origin. — From  the  articular  processes  of  the  three  or 
four  lower  cervical  and  the  transverse  processes  of  the 
four  or  five  upper  dorsal  vertebrae. 

Insertion. — Into  the  mastoid  process  of  the  temporal 
bone. 


132  A  MANUAL   OF  ANATOMY. 

Nerve  Supply. — The  external  branches  of  the  posterior 
divisions  of  the  cervical  nerves. 

Action. — To  extend  the  head  and  neck,  if  both  act ;  to 
flex  the  head  and  neck  laterally  and  rotate  them  to  the 
same  side,  if  one  acts. 

Complexus.     Fig.  76. 

Origin. — The  transverse  processes  of  the  upper  six 
dorsal  and  seventh  cervical  vertebrae,  from  the  articular 
processes  of  the  lower  three  or  four  cervical  vertebrae. 

Insertion. — Into  the  surface  of  the  occipital  bone  between 
the  inner  halves  of  the  superior  and  inferior  curved  lines. 

The  inner  third  of  the  complexus  is  also  called  the  bi- 
venter  cervicis,  inasmuch  as  its  muscular  portions  are 
separated  by  a  median  tendon. 

Nerve  Supply. — The  upper  three  or  four  cervical  nerves, 
through  their  posterior  divisions. 

Action. — To  extend  the  head  when  both  act.  If  one  acts 
it  flexes  the  head  laterally. 

DISSECTION. 
Divide  the  complexus  and  the  trachelomastoid  at  their  cranial  attachments, 
and  the  levator  anguli  scapulae  at  its  spinal  attachments.  The  rhomboids  and 
the  serratus  posticus  superior  should  have  been  removed  by  this  time  by  the 
one  dissecting  the  upper  extremity.  Carefully  remove  the  dense  fascia  which 
covers  the  muscles  forming  the  suboccipital  triangle  and  fills  in  the  space 
between  them.  In  dissecting  off  the  fascia  covering  the  suboccipital  triangle 
and  the  deep  muscles  of  the  neck,  save  the  princeps  cervicis  and  the  profunda 
cervicis  arteries,  and  recognize  their  anastomo.sis  with  each  other  and  with  the 
vertebral  artery  through  the  triangle.  Look  for  the  suboccipital  nerve  and 
vertebral  artery  within  the  triangle. 

The  Suboccipital  Triangle.      Fig.  19. 

This  triangle  is  formed  by  the  superior  oblique  externally, 
the  inferior  oblique  below,  and  the  rectus  capitis  posticus 
major  internally. 


Fig.  19.  The  Suboccipital  Triangle.  [From  a  specimen  in  the  museum  of  the 
University  Medical  College.]— a,  External  occipital  protuberance,  b,  Superior  curved 
line,  c,  Rectus  capitis  posticus  minor,  rf,  Obliquus  superior.  ^,  Rectus  capitis  posticus 
major.  /,  Obliquus  inferior,  g.  Vertebral  artery  winding  around  the  superior  articular 
process  of  the  atlas,  h.  Transverse  process  of  the  atlas.  /,  Spinous  process  of  the 
axis. 


134  A  MANUAL   OF  ANATOMY. 

Within  it  are  found  the  suboccipital  nerve,  the  vertebral 
artery,  and  their  branches.  Its  floor  is  formed  by  the  pos- 
terior arch  of  the  atlas  and  the  occipito-atlantal  ligament. 

Obliquus  Capitis  Superior.     Fig.  19. 

Origin. — From  the  upper  surface  of  the  transverse  pro- 
cess of  the  atlas. 

Insertion. — Into  the  occipital  bone  between  the  outer 
halves  of  the  curved  lines. 

Nerve  Supply. — The  suboccipital. 

Action. — To  extend  and  slightly  flex  the  head  laterally. 

Obliquus  Capitis  Inferior.      Fig.  19. 

Origin. — From  the  side  of  the  spine  of  the  axis. 

Insertion. — Into  the  lower,  posterior  surface  of  the  trans- 
verse process  of  the  atlas. 

Nerve  Stipply. — The  suboccipital. 

Action. — To  rotate  the  atlas  and  head  upon  the  axis ;  to 
slightly  flex  the  atlas  upon  the  axis. 

Rectus  Capitis  Posticus  Major.     Fig.  19. 

Origin. — From  the  spinous  process  of  the  axis. 

Insertion. — Into  the  middle  third  of  the  inferior  curved 
line  of  the  occipital  bone. 

Nerve  Supply. — The  suboccipital. 

Action. — To  extend  the  head  upon  the  neck  when  both 
act ;  when  one  acts,  in  addition  to  the  extension,  it  rotates 
the  head  to  the  same  side. 
Rectus  Capitis  Posticus  Minor.      Fig.  19. 

Origin. — From  the  side  of  the  tubercle  upon  the  posterior 
arch  of  the  atlas. 

Insertion. — Into  the  inner  third  of  the  inferior  curved  line 
of  the  occipital  bone,  and  the  depression  anterior  to  it. 

Nerve  Supply. — The  suboccipital  nerve. 

Action. — To  extend  the  head. 


THE  HEAD  AND  NECK,  POSTERIOR.  135 

Semispinalis  Colli.     Fig.  76. 

Origin. — From  the  transverse  processes  of  the  five  or  six 
upper  dorsal  vertebrse. 

Insertion. — Into  the  spinous  processes  of  the  second  to 
the  sixth  cervical  vertebra,'. 

Nerve  Supply. — The  internal  branches  of  the  posterior 
divisions  of  the  lower  cervical  nerves. 

Actioji. — Both  acting,  they  extend  the  cervical  vertebrae. 
One  acting,  extends,  and  rotates  the  neck  to  the  opposite 
side. 

Transversalis  Colli.     Fig.  yG. 

Origi)i. — From  the  transverse  processes  of  the  five  or 
six  upper  dorsal  vertebrae. 

Insertion. — Into  the  posterior  tubercles  of  the  transverse 
processes  of  the  cervical  vertebrae  from  the  second  to  the 
sixth. 

Nerve  Supply. — The  external  branches  of  the  posterior 
divisions  of  the  lower  cervical  and  upper  dorsal  nerves. 

Action. — Both,  extend  the  neck  ;  one,  rotate  the  cervical 
vertebrae  to  the  same  side  and  flex  them  laterally. 

Cervicalis  Ascendens.      Fig.  76. 

Origin. — From  the  four  or  five  upper  ribs  near  their 
angles. 

Insertion. — Into  the  transverse  processes  of  the  fourth, 
fifth,  and  sixth  cervical  vertebrae. 

Nerve  Supply. — The  external  branches  of  the  posterior 
divisions  of  the  lower  cervical  and  upper  dorsal  nerves. 

Action. — To  extend  the  lower  cervical  vertebrae,  to  raise 
the  ribs,  and  so  aid  inspiration  ;  one  acting,  to  flex  the 
lower  cervical  vertebrae  laterally. 

The  Deep  Cervical  Artery  {Profunda  Cervicis).      See  page 
1 13  for  source. 


136  A  MANUAL   OF  ANATOMY. 

It  appears  in  the  dissection  of  the  posterior  region  of  the 
neck,  under  the  complexus  and  upon  the  semispinalis  ;  its 
course  is  vertically  upward  to  anastomose  at  the  suboccip- 
ital triangle  with  the  deep  branch  (continuation)  of  the 
princeps  cervicis  of  the  occipital.  The  artery  in  its  course 
enters  into  anastomoses  with  branches  of  the  vertebral. 

The  Deep  Cervical  Vein  (^Profunda  Cervicis  Vein). 

This  begins  in  the  suboccipital  triangle  by  the  confluence 
of  smaller  veins  from  the  surrounding  parts.  It  descends 
along  the  course  of  the  deep  cervical  artery,  and  opens  into 
the  innominate  or  vertebral  veins. 

The  Vertebral  Vein.      See  page  1 1 1 . 

In  the  suboccipital  triangle  the  deep  cervical  and  verte- 
bral veins  freely  communicate. 

The  vertebral  receives  tributaries  from  within  the  spinal 
canal,  the  vertebrae,  and  muscles. 

The  Suboccipital  Nerve. 

The  posterior  division  of  the  first  cervical  nerve  passes 
backward  between  the  vertebral  artery  and  the  posterior 
arch  of  the  atlas,  then  through  the  suboccipital  triangle  to 
the  deep  surface  of  the  complexus  muscle. 

It  supplies  the  muscles  forming  the  triangle,  the  rectus 
capitis  posticus  minor,  the  complexus,  and  sends  a  twig  to 
the  great  occipital  nerve. 

The  Deep  Cervical  Fascia. 

The  deep  cervical  fascia  consists  of  the  membranous 
sheaths  of  muscles,  the  covering  of  glands  (capsules),  the 
firm  supporting  encasement  of  vessels  and  the  thinner  ones 
of  nerves,  and  the  connecting  processes  (or  ligaments) 
which  join  the  detached  to  the  fixed  parts  of  the  head  and 
neck. 


THE  HEAD  AND  NECK,  POSTERIOR. 


All  these  separate  portions  belong  to  the  same  filling  of 
connective  tissue,  and  are  grouped  under  the  name  of  the 
deep  cervical  fascia. 

These  parts  are  continuous  with  one  another,  and  are 
only  divisions  of  the  general  connective  tissue  of  the  neck, 


Diag.  9.  A  Diagram  of  the  Cervical  Fascia  below  the  Hyoid  Bone. 
{Modified  from  Gray^ — i,  Sternohyoid.  2,  Omohyoid.  3,  Sternothyroid.  4, 
Trachea.  5,  Thyroid  gland.  6,  Sternomastoid.  7,  CEsophagus.  8.  Common  carotid. 
9,  Pneumoga.stric  nerve.  10,  Internal  jugular.  11,  Longus  colli.  12,  Body  of  the  sixth 
cervical  vertebra.  13,  Vertebral  foramen.  14,  Scalenus  anticus  and  rectus  capitis 
anticus  major.  15,  Scalenus  medius  and  posticus.  16,  Vertebral  canal.  17,  Semi- 
spinalis  colli.  18.  Complexus  (and  biventer).  19,  Splenius  colli.  20,  Levator  anguli 
scapulae.  21.  Splenius  capitis.  22,  Trapezius,  a,  First  layer  enclosing  sterno- 
mastoid. b,  Second  layer  enclosing  the  subhyoid  muscles,  c,  Third  layer  enclosing 
the  vessels,  thyroid  gland,  trachea,  and  oesophagus,  d.  Fourth  (prevertebral)  layer. 
e,  Ligamentum  nuchae. 

SO  in  order  to  properly  describe  it,  to  have  a  starting  point, 
its  description  must  be  taken  up  in  parts  and  according  to 
an  arbitrary  classification. 


138  A  MANUAL   OF  ANATOMY. 

The  fascia  is  described  in  several  layers. 

(i)  The  first  layer  of  the  cervical  fascia. 

This  starts  behind  from  the  spinous  processes  of  the 
cervical  vertebrae  (through  the  ligamentum  nuchse),  encloses 
the  trapezius,  receives  a  membranous  expansion  from  the 
transverse  processes  of  the  cervical  vertebrae  at  the  side  of 
the  neck,  passes  forward  to  the  posterior  border  of  the 
sternomastoid  muscle,  splits  into  two  layers  which  enclose 
the  muscle  and  unite  at  its  anterior  margin,  passes  onward 
and  becomes  continuous  at  the  middle  line  with  the  similar 
layer  from  the  other  side. 

Above,  this  first  layer  is  attached  to  the  lower  border  of 
the  jaw  (from  its  angle  being  continued  to  the  styloid  pro- 
cess of  the  temporal  bone  forming  the  stylomaxillary  liga- 
ment), and  passing  over  the  masseter  muscle  and  parotid 
gland  as  the  masseteric  atid  parotid  fascias,  is  attached  to  the 
lower  border  of  the  zygoma.  Behind  the  ear  this  layer  is 
attached  to  the  superior  curved  line  of  the  occipital  bone 
and  the  mastoid  process  of  the  temporal  bone  (externally 
and  internally).  Below,  to  the  front  of  the  clavicle,  outer 
margin  of  the  acromion  process,  and  the  middle  portion  of 
the  spine  of  the  scapula.    . 

In  the  middle  line  the  first  layer  is  also  fastened  to  the 
hyoid  bone. 

(2)  The  second  layer.  This  is  given  off  from  the  inner 
surface  of  the  first  layer  along  the  posterior  border  of  the 
sternomastoid  muscle. 

It  passes  forward,  enclosing  the  omohyoid,  sternohyoid, 
and  sternothyroid  muscles,  and  unites  in  the  median  line 
with  a  similar  layer  from  the  other  side,  also  with  the  first 
layer. 

Above,  it  reaches  to  the  hyoid  bone.  Below,  it  is  at- 
tached to  the  inner  marg-in  of  the  manubrium  and  clavicle. 


THE  HEAD  AND  NECK,  POSTERIOR.  139 

It  also  extends  downward  to  the  cartilage  of  the  first  rib, 
this  portion  forming  the  loop  by  which  the  tendon  and 
posterior  belly  of  the  omohyoid  muscle  is  kept  in  position. 

Between  layers  number  one  and  two  is  left  a  triangular 
space — Burns'  space — that  has  no  width  above,  but  below 
is  represented  by  the  space  between  the  posterior  margins 
of  the  sternomastoid.  This  space  contains  fat,  lymphatic 
glands,  the  anterior  jugular  vein,  and  connective  tissue  to 
keep  them  in  position. 

It  is  also  stated  that  the  second  layer  is  continued  under 
the  clavicle,  splits  to  enclose  the  subclavius  muscle,  and 
reunites  to  form  the  costocoracoid  membrane.  That  the 
sheath  for  the  subclavian  vein  is  derived  from  this  second 
layer,  while  for  the  artery  it  comes,  as  stated  below,  from 
the  third  layer. 

(3)  The  third  layer  of  the  cervical  fascia.  This  invests 
the  carotid  vessels,  arteries,  and  internal  jugular  vein,  pneu- 
mogastric  nerve,  thyroid  gland,  trachea,  oesophagus,  and 
many  other  structures.  This  is  also  given  off  from  the 
under  surface  of  the  first  layer  behind  the  sternomastoid 
muscle.  It  passes  forward,  splitting  to  enclose  the  internal 
jugular  vein,  pneumogastric  nerve,  carotid  arteries  (forming 
their  sheaths),  thyroid  gland  (forming  its  capsule),  the 
trachea,  and  oesophagus,  and  finally  unites  in  the  middle 
line  with  corresponding  layers  from  the  other  side. 

Besides  the  structures  above  enumerated  this  layer  en- 
sheaths  all  the  structures  found  between  the  under  surface 
of  the  second  layer  and  in  front  of  the  prevertebral  (fourth) 
layer. 

Above,  this  third  layer  passes  up  to  the  base  of  the  skull 
and  is  attached  to  the  basilar  and  jugular  processes  of  the 
occipital  bone,  the  petrous  process  of  the  temporal  bone,  the 
spinous  and  pterygoid  processes  of  the  sphenoid  bone. 


140  A  MANUAL   OF  ANATOMY. 

Below,  it  passes  along  with  the  great  vessels  (trachea 
and  oesophagus)  into  the  thorax,  forming  their  sheaths,  and 
becomes  continuous  with  the  fibrous  layer  of  the  pericar- 
dium. 

Laterally,  this  fascia  passes  outward  under  the  clavicle 
with  the  subclavian  artery  and  vein  and  brachial  plexus, 
forming  their  sheath.  In  the  axilla  it  receives  the  name  of 
that  region  (axillary  sheath). 

(4)  The  fourth  or  prevertebral  layer  of  fascia.  The 
name  indicates  its  position  to  be  in  front  of  the  vertebrae 
(and  their  muscles).  It  lies  immediately  behind  the  third 
layer,  and  covers  over  the  rectus  capitis  anticus  major 
and  minor,  and  longus  colli  muscles. 

Above,  it  is  attached  to  the  basilar  process  of  the  occipi- 
tal bone.  Laterally,  to  the  inner  surface  of  the  first  layer 
along  the  side  of  the  neck  ;  below,  it  passes  into  the  thorax 
behind  the  oesophagus,  and  extends  into  the  posterior  me- 
diastinum. 

While  these  various  layers  are  described,  it  should  be 
remembered  that  they  are  so  described  more  for  convenience 
and  to  indicate  a  general  lamination,  than  to  mean  that 
these  layers  will  be  found  as  distinct  and  separated  from 
each  other  as  the  description  would  indicate.  On  the  con- 
trary, all  these  layers  blend  wherever  they  come  in  contact, 
for  the  deep  cervical  fascia  is  only  a  part  of  the  connective- 
tissue  system  of  the  body,  whose  function  is  to  connect  and 
support  the  various  organs  between  which  it  is  developed. 
Consequently,  the  student  will  obtain  a  more  correct  view 
of  the  cervical  fascia  (as  well  of  any  other)  if  he  will  imagine 
all  the  muscles,  veins,  arteries,  and  nerves  of  the  neck 
removed,  and  the  sheaths,  capsules,  and  envelopes  of 
these  and  the  connective  tissue  which  bind  them  all  in 
position   only   remaining.     This   will  then   show    that  the 


THE  HEAD  AND  NECK,  POSTERIOR.  141 

separate  parts  usually  described  arc  only  so  separated 
by  anatomists  for  convenience  of  description,  and  that  such 
divisions  do  not  exist  as  separate  from  the  other  parts  or 
layers,  but  that  all  are  united  into  a  complicated  whole. 

The  influence  that  the  cervical  fascia  has  upon  determin- 
ing the  course  of  certain  surgical  affections,  as  abscesses 
and  tumors,  is  a  good  deal  more  theoretical  than  real. 
It  is  found  in  practice  that  abscesses  from  cervical  caries 
may  descend  into  the  thorax,  but  usually  will  point  along 
the  lateral  region  of  the  neck  if  above  the  sixth  cervical 
vertebra.  The  postpharyngeal  abscess  will  usually  point 
in  the  pharynx.  Abscesses  in  the  lower  part  of  the  neck, 
unless  behind  the  third  layer  of  fascia,  will  usually  point 
above  the  clavicle  or  sternum. 

The  Pharynx  (concluded),  Larynx,  and  Nasal  Fossae. 

DISSECTION. 

The  dissection  of  the  back  of  the  neck  having  been  completed,  the  remain- 
ing muscles  which  hold  the  head  to  the  spine  should  be  severed,  and  the  skull 
separated  from  the  atlas  by  the  division  of  the  connecting  ligaments,  or  the  skull 
should  be  sawn  transversely  across  in  front  of  the  foramen  magnum.  The 
trachea  should  be  separated  from  the  larynx  by  dividing  it  just  below  the  cri- 
coid cartilage  and  the  oesophagus  cut  across  at  the  same  level.  Now  remove 
the  head  and  attached  portions  of  the  pharynx,  larynx,  and  the  arteries,  veins, 
and  nerves,  which  emerge  from  the  base  of  the  skull. 

Identify  all  those  structures  which  have  been  found  already  in  the  dissec- 
tion of  the  deep  neck. 

Divide  the  pharynx  along  the  median  raphe  and  open  its  cavity. 

The  Structures  seen  on  Opening  the  Pharynx. 

Posterior  nares,  separated  by  the  vomer,  and  within 
which  can  be  seen  the  posterior  extremities  of  the  middle 
and  inferior  turbinated  bones. 

The  opening  for  the  Eustachian  tube  is  behind  the 
lower  portion  of  the  posterior  nares  ;  it  leads  into  the  middle 
ear. 


142  A  MANUAL   OF  ANA  TOMY. 

The  cartilage  which  constitutes  the  anterior  portion  of 
the  Eustachian  tube  forms  a  prominent  ring  around  the 
opening  orifice  called  the  tubal  eminence. 

Behind  the  Eustachian  tube  opening  is  a  blind  pit,  the 
fossa  of  Rosenmiiller. 

Below  the  posterior  nares  the  soft  palate  hangs  down- 
ward and  terminates  medianly  in  the  uvula.  The  soft 
palate  serves  to  shut  off  the  nasal  passages  from  the 
pharynx  in  deglutition. 

Laterally  the  free  margin  of  the  soft  palate  is  thrown 
into  two  prominent  arches  ;  the  posterior,  descending  to 
the  pharyngeal  wall ;  the  anterior,  to  the  side  of  the  tongue, 
leaving  a  hollow  between  them.  These  arches  are  called 
the  anterior  and  posterior  arches  of  the  fauces,  or 
the  anterior  and  posterior  palatine  arches.  The  depres- 
sion between  them  is  the  tonsillar  recess,  and  lodges  the 
tonsil. 

The  posterior  arch  is  produced  by  the  palatopharyngeus, 
the  anterior  by  the  palatoglossus  muscle. 

The  tonsils  are  two  oval-shaped  masses  of  spongy  ade- 
noid tissue,  situated  within  the  two  palatine  arches.  Their 
size  in  the  cadaver  is  never  as  large  as  in  the  living,  conse- 
quently their  relative  size  can  best  be  estimated  from  an 
examination  of  the  throats  of  friends. 

The  roof  of  the  pharynx  is  occupied  by  an  adenoid  mass, 
the  pharyngeal  tonsil,  which  in  children  sometimes 
assumes  very  large  proportions. 

The  base  of  the  tongue  is  seen  below  the  soft  palate. 
The  opening  of  the  mouth  posteriorly  into  the  pharynx  is 
called  the  isthmus  fauciuni.  It  is  bounded  by  the  soft 
palate  above,  the  faucial  arches  and  tonsils  laterally,  and 
the  base  of  the  tongue  below.  Upon  the  base  of  the 
tongue  will  be  seen  in  the  middle  line  the  foramen  caecum. 


THE  HEAD  AND  NECK,  POSTERIOR.  143 

in  front  of  this  blind  depression  the  "  V-shaped  "  group  of 
circumvallate  papillae. 

A  third  mass  of  adenoid  tissue  is  seen  at  the  base  of  the 
tongue  and  in  front  of  the  epiglottis  ;  this  is  the  lingnal 
tonsil. 

Below  and  behind  the  base  of  the  tongue  stands  the  epi- 
glottis to  protect  the  opening  of  the  larynx,  which  presents 
posterior  and  inferior  to  it. 

The  epiglottis  is  connected  to  the  base  of  the  tongue  by 
the  general  covering  of  mucous  membrane  which  is  thrown 
into  three  folds,  one  in  the  medial  line  and  two  laterally, 
which  are  called  the  median  (fraenum  epiglottidis)  and 
lateral  glosso-epiglottic  folds.  On  both  sides  of  the  frae- 
num epiglottidis  is  a  shallow  depression — the  glosso-epi- 
glottic pouch. 

From  the  sides  of  the  epiglottis  backward  to  the  top  of 
the  larynx  the  mucous  membrane  is  thrown  into  a  promi- 
nent ridge,  the  aryteno-epiglottic  fold.  The  upper  mar- 
gins and  cornua  of  the  thyroid  cartilage  can  be  easily  appre- 
ciated. 

DISSECTION. 

Remove  the  mucous  membrane  which  covers  the  interior  of  the  pharynx, 
the  posterior  surface  of  the  soft  palate,  and  the  posterior  faucial  arches. 

In  dissecting  the  muscles  of  the  palate  and  the  pharynx  (interior),  it  must 
be  remembered  that  these  are  very  thin,  and  their  outlines  not  at  all  as  distinct 
as  the  illustrations  in  the  text-books  would  lead  one  to  think.  The  student 
should  do  the  best  he  can  with  the  aid  of  such  illustrations  and  the  descriptive 
anatomy  to  find  the  various  parts. 

Palatophary  ngeus . 

The  thin  muscular  layer  is  attached  to  the  soft  palate  near 
the  median  line  and  arches  outward  and  downward,  form- 
ing the  posterior  palatine  arch,  to  be  attached  below  to  the 
posterior  border  of  the  thyroid  cartilage  and  the  lateral  wall 
of  the  pharynx.     At  the  soft  palate  the  fibres  of  the  muscle 


144  A  MANUAL   OF  ANATOMY. 

are  separated  by  the  insertion  of  the  levator  palati.  The 
muscle  acts  to  elevate  the  pharynx  and  larynx,  or  to 
depress  the  soft  palate. 

Azygos  Uvulae. 

A  few  muscular  fibres  in  the  median  line  reaching  from 
the  posterior  nasal  spine  to  the  tip  of  the  uvula.  Its  func- 
tion is  to  elevate  the  uvula. 

Levator  Palati. 

This  arises  from  the  under  surface  of  the  petrous  portion 
of  the  temporal  bone  in  front  of  the  carotid  canal  and  from 
the  cartilage  of  the  Eustachian  tube.  It  is  inserted  into 
the  soft  palate  along  the  middle  line. 

The  action  is  to  raise  the  soft  palate  and  close  the  posterior 

nares. 

DISSECTION. 
Remove  the  levator  palati  and  the  upper  portion  of  the  palatopharyngeus. 
This  exposes  the  tensor  palati  muscle  and  the  ascending  palatine  artery. 

Tensor  Palati. 

Arises  from  the  scaphoid  fossa  of  the  sphenoid  bone,  its 
tendon  winds  around  the  hamular  process  of  the  internal 
pterygoid  plate  and  expands  into  a  second  muscular  portion, 
which  is  attached  along  the  posterior  margin  of  the  hard 
palate  and  into  the  median  raphe  of  the  soft  palate. 

For  the  ascending  palatine  artery,  see  Facial,  page  95. 

DISSECTION. 
Remove  the  mucous  membrane  from  the  anterior  pillar  of  the  fauces  and 
expose  the  palatoglossus  muscle  which  forms  this  pillar. 

Palatoglossus. 

Extends  from  the  anterior  surface  of  the  soft  palate  to 
the  side  of  the  base  of  the  tongue,  where  it  interlaces  with 
the  styloglossus  muscle.      Its  action  is  to  draw  the   sides 


THE  HEAD  AND  NECK,  POSTERIOR.  145 

of  the  soft  palate  downward   and  forward,  or  the  tongue 
upward  and  backward. 

The  Eustachian  Tube. 

The  cartilaginous  portion  of  this  tube  wall  be  exposed 
from  its  anterior  part,  lying  between  the  levator  and  tensor 
palati  muscles  and  giving  origin  to  some  fibres  of  these 
muscles.  The  palatopharyngeus  also  has  a  small  bundle 
arising  from  the  tube,  the  salpingopJiaryngcus . 

The  opening  of  the  Eustachian  tube  is  in  the  shape  of  a 
vertical  slit,  and  the  canal  leads  into  the  cavity  of  the  middle 
ear. 

DISSECTION. 

Separate  the  tongue  and  larynx  from  the  skull.  Remove  any  remains  of  the 
oesophagus.  Identify  the  epiglottis,  hyoid  bone,  thyroid,  cricoid,  and  (upon 
the  top  of  the  cricoid  behind)  the  small  arytenoid  cartilages.  Forward  and 
upward  from  the  arytenoid  cartilages  pass  the  aryteno-epiglottic  folds  to  the 
side  of  the  epiglottis.  Between  these  folds  is  the  upper  opening  of  the 
larynx. 

Looking  into  this  opening  the  canal  of  the  larynx  will  be  seen  to  be  con- 
stricted at  two  places  by  two  anteroposterior  bands.  The  upper  pair  are  the 
false  vocal  cords  and  the  lower  pair  the  true  vocal  cords. 

The  slit  between  the  vocal  cords  is  the  rima  glottidis  and  varies  in  width 
according  to  the  approximation  of  the  vocal  cords. 

The  true  vocal  cords  may  be  made  to  approach  or  diverge  from  each  other 
by  depressing  or  elevating  the  thyroid  upon  the  cricoid  cartilage,  or  by  rotat- 
ing the  arytenoid  cartilages  upon  the  cricoid  cartilages. 

The  description  of  the  cartilages  of  the  larynx  is  omitted 
from  this  manual  as  being  to  the  larynx  what  the  bones  are 
to  the  other  parts  of  the  body. 

External  Structures. 
Muscles. 

Cricothyroid. 

Origin. — From  the  anterior  part  of  the  cricoid  cartilage. 
Insertion. — Into  the  inferior  border  of  the  thyroid  carti- 
lage. 

lO 


146  A  MANUAL   OF  ANATOMY. 

Action. — To  approximate  the  two  cartilages  and  thus 
make  tense  the  vocal  cords. 

Posterior  Crico-arytenoid. 

Arises  from  the  quadrilateral  posterior  surface  at  the 
side  of  the  median  ridge  of  the  cricoid  cartilage. 

It  is  inserted  into  the  outer  angle  of  the  base  of  the 
arytenoid  cartilage.  The  action  is  to  slacken  the  vocal 
cords  and  widen  the  rima  glottidis. 

Arytenoideus. 

Crosses  from  one  arytenoid  cartilage  to  the  other.  In 
action  it  draws  together  the  arytenoid  cartilages,  thus 
narrowing  the  rima  glottidis. 

Aryteno-epiglottidis. 

The  name  applied  to  a  small  bundle  of  fibres  connecting 
the  arytenoid  cartilage  with  the  aryteno-epiglottic  fold.  It 
is  a  part  of  the  arytenoideus. 

Arteries  passing  into  the  larynx. 

The  superior  laryngeal  branch  of  the  superior  thyroid 
and  the  inferior  laryngeal  branch  of  the  inferior  thyroid 
artery. 

Nerves  of  the  larynx. 

The    superior    and    inferior    laryngeal    branches    of  the 

pneumogastric. 

DISSECTION. 

Remove  these  external  muscles,  clean  the  fibrous  membranes  connecting 
the  thyroid  cartilage  to  the  hyoid  bone  (thyrohyoid  membrane),  and  that 
uniting  the  cricoid  and  thyroid  cartilages  (cricothyroid  membrane).  These 
membranes  have  to  be  divided  in  the  operations  of  opening  the  larynx  or  the 
larynx  and  trachea. 

Remove  one-half  of  the  larynx. 

Above  the  false  vocal  cord  is  the  fossa  innominata ;  be- 
tween the  false  and  true  cords  the  ventricle. 
Muscles  of  the  Interior  of  the  Larynx. 


THE  HEAD  AXD  AECK,  POSTERIOR.  147 

Lateral  Crico-arytenoid. 

From  the  lateral  upper  border  of  the  cricoid  cartilage, 
into  the  muscular  process  of  the  arytenoid  cartilage.  The 
action  is  to  approximate  the  v'ocal  cords  by  drawing  the 
arytenoid  cartilages  together. 

Thjrro-arytenoid. 

By  a  vertical  origin  from  the  inner  surface  of  the  thy- 
roid cartilage  near  the  median  line.  It  is  attached  pos- 
teriorly into  the  base  and  side  of  the  arytenoid  cartilage. 
The  muscle  consists  of  two  portions,  an  upper  and  a  lower. 
The  lower  portion  lies  parallel  with  the  true  vocal  cord 
and  some  of  its  fibres  pass  into  it. 


ACTION  OF  THE  MUSCLES  MOVING   THE  VOCAL  CORDS. 
[Eroin  Holden.) 

Cricothyroidei, To  stretch  the  vocal  cords. 

Thyro-arytenoidei,       To  relax  the  vocal  cords  and  place 

them  in  the  vocalizing  position. 

Crico-arytenoidei  postici,    .    .    .  Dilate  the  glottis. 

Crico-arytenoidei  laterales,  .  .  Draw  together  the  arytenoid  carti- 
lages. 

Arytenoideus,  Draw  together  the  aiytenoid  carti- 
lages. 

Aryteno-epiglottidei, Contract  the  upper  opening  of  the 

larynx. 

Nerve  Supply  for  the  Muscles  of  the  Larynx. 

The  external  branch  of  the  superior  laryngeal  suppHes 
the  cricothyroid.  The  inferior  laryngeal  nerve  supplies  all 
the  remaining  muscles  of  the  larynx. 

The  muscles  connecting  the  epiglottis  with  the  thyroid 
cartilage  (thyro-epiglottideus,  with  the  aryteno-epiglot- 
tideus  superior  and  inferior)  are  thin  bands  of  muscular 
fibres  which  need  not  detain  the  creneral  dissector. 


148  A  MANUAL  OF  ANATOMY. 

The  Nasal  Fossae.     Figs.  12,  13. 

DISSECTION. 

Take  the  lower  segment  of  the  skull  and  divide  it  with  a  saw  anteroposte- 
riorly  just  at  one  side  of  the  vomer. 

Study  the  nasal  fossae.  Each  nasal  fossa  is  divided  by  the  superior,  mid- 
dle, and  inferior  turbinated  bones  into  the  superior,  middle,  and  inferior 
meatus. 

The  nasal  duct  opens  into  the  anterior  part  of  an  inferior  meatus,  the  infundi- 
bulum  opening  of  the  frontal  sinus  and  anterior  ethmoidal  cells  is  in  the  anterior 
part  of  a  middle  meatus,  and  at  the  middle  portion  is  the  opening  of  the  max- 
illary sinus,  or  the  antrum  of  Highmore. 

In  the  anterior  part  of  the  superior  meatus  is  the  opening  of  the  posterior  eth- 
moidal cells,  and  in  its  posterior  portion  the  opening  of  the  sphenoidal  sinus. 

It  will  hardly  repay  the  student  to  undertake  the  dissec- 
tion of  the  small  vessels  and  nerves  which  are  found  upon 
the  walls  of  the  nasal  fossa. 

Upoiz  the  Septum. — The  septum  is  crossed  from  above 
downward  and  forward  by  the  nasopalatine  nerve  and 
artery  and  the  septal  branch  of  the  nasal  nerve. 

Each  spongy  turbinated  mass  is  provided  with  an  artery, 
which  comes  from  the  nasopalatine  branches  of  the  internal 
maxillary  artery. 

DISSECTION. 

On  a  dry  skull  (sawn  through  anteroposteriorly)  locate  the  sphenopalatine 
foramen.  In  the  specimen  dissect  off  the  mucous  membrane  over  a  corres- 
ponding area  and  expose  the  sphenopalatine  foramen  and  the  small  artery  and 
nerves  it  transmits. 

Remove  the  mucous  membrane  carefully  from  the  nasal  fossa  under  the 
cribriform  plate  of  the  ethmoid  and  find  the  nerves  and  arteries  entering  at  this 
point. 

Through  the  sphenopalatine  foramen  the  nasopalatine  or  sphenopalatine 
artery  and  nerve  enter  the  nasal  fossa.  They  divide  into  two  branches,  an  ex- 
ternal and  internal,  to  the  outer  wall  and  the  septum  (inner  wall)  of  the  nose. 

The  sphenopalatine  artery  is  the  terminal  branch  of 
the  internal  maxillary  artery  and  enters  the  sphenopalatine 


THE  HEAD  AND  NECK,  POSTERIOR.  ]49 

foramen  with  the  sphenopalatine  branch  of  Meckel's  gan- 
glion. The  artery  and  nerve  are  distributed  to  the  outer 
wall  and  the  septum  of  the  nose.  The  septal  branch  of 
the  artery  anastomoses  in  front  with  the  anterior  palatine 
artery,  w^hich  runs  along  the  roof  of  the  mouth  and  turns 
up  through  the  transversely  paired  foramen  (Stenson's). 

The  nasal  nerve  (see  page  56)  enters  the  nose  through 
the  nasal  slit  with  the  anterior  ethmoidal  artery.  The 
nerve  supplies  branches  to  the  outer  wall  and  the  septum 
of  the  nose.  The  posterior  ethmoidal  artery  enters  the 
nasal  cavity  posterior  to  the  nasal  slit,  and  with  the  anterior 
is  distributed  to  the  upper  part  of  the  internal  and  ex- 
ternal nasal  wall. 

DISSECTION. 

With  the  bone  cutters  or  a  chisel  carefully  remove  the  bone  surrounding  the 
sphenopalatine  foramen,  the  orbital  process  of  the  palate,  and  the  body  of  the 
sphenoid  until  the  foramen  rotundum  is  reached  and  the  superior  maxillary 
nerve  is  exposed.  Beneath  the  nerve  as  it  is  crossing  the  sphenomaxillary 
fossa  is  the  small  ganglion  of  Meckel,  or  the  sphenomaxillary  ganglion. 

In  the  sphenomaxillary  fossa  the  internal  maxillary  artery  divides  into  nu- 
merous branches.     See  page  122. 

After  finding  the  ganglion,  its  large  posterior  branch  (the  Vidian  nerve) 
should  be  followed  back  to  and  through  the  Vidian  canal  (by  cutting  away  the 
bone  as  necessary). 

The  various  branches  of  the  ganglion  will  have  to  be  followed  in  the  same 
way  by  removing  piecemeal  the  bone  covering  them. 

Finish  this  specimen  by  tracing  the  superior  maxillary  nerve  through  the 
infra-orbital  groove  and  canal  and  out  through  the  foramen  to  the  exterior  of 
the  face,  also  its  dental  branches.  In  this  dissection  the  antrum  of  Highmore 
is  opened  and  should  be  studied  from  the  descriptions  of  the  bones  in  a  dry 
state. 

The  Superior  Maxillary  Nerve.      Figs.  10,  11. 

This  is  the  second  branch  from  the  front  of  the  Gasserian 
ganglion  of  the  fifth  cranial  nerve. 

It  leaves  the  skull  through  the  foramen  rotundum  and 
enters  the  sphenomaxillary  fossa.      Continuing  its  course 


150  A  MANUAL   OF  ANATOMY. 

forward,   it  lies    in   the  infra-orbital  groove,   then  in    the 
infra-orbital  canal,  through  which  it  passes,  to  emerge  upon 
the  face  at  the  infra-orbital  foramen  and  supply  the  mid 
region  of  the  face  with  sensory  branches. 
Branches  of  the  Siipcrior  Maxillary  Nerve. 

(i)  Within  the  skull,  one  or  two  recurrent  filaments 
supplying  the  dura. 

(2)  In  the  sphenomaxillary  fossa.  {a)  The  orbital  or 
temporomalar  nerve.  Enters  the  orbit  through  the 
sphenomaxillary  fissure,  and  divides  into  the  temporal 
and  malar  branch.  The  temporal  branch  passes  through 
the  temporal  foramen  in  the  malar  bone,  enters  the 
temporal  fossa,  passes  through  it  to  pierce  the  temporal 
fascia  above  the  zygoma  and  be  distributed  to  the  integu- 
ment of  the  anterior  part  of  the  temporal  region.  The 
malar  branch  passes  through  the  malar  foramen  of  the 
malar  bone  to  supply  the  integument  over  that  bone.  (^) 
The  posterior  superior  dental  nerve  divides  into  two 
branches,  which  descend  along  the  posterior  surface  of  the 
superior  maxillary  bone,  enter  the  posterior  dental  foramina, 
and  supply  the  molar  teeth  and  mucous  membrane  adjacent 
to  them,  {c)  The  middle  superior  dental  nerve  is  given  off 
the  superior  maxillary  in  the  posterior  part  of  the  infra- 
orbital canal,  runs  downward  and  forward  in  a  special  canal 
on  the  outer  wall  of  the  antrum  to  supply  the  bicuspid 
teeth.  ((^)  The  anterior  superior  dental  nerve  is  given  off 
at  the  anterior  part  of  the  infra-orbital  canal,  and  descends 
in  a  canal  on  the  anterior  wall  of  the  antrum  to  supply  the 
incisive  and  the  canine  teeth  and  gives  off  the  nasal  branch 
to  the  mucous  membrane  of  the  floor  and  wall  of  the 
anterior  part  of  the  inferior  meatus.  The  three  dental 
nerves  have  loops  of  communication  with  each  other,  thus 
forming  the    superior    dental    plexus.      {e)    The   terminal 


THE  HEAD  AND  NECK,  POSTERIOR.  151 

branches  on  the  face  are  four  labial  (usually),  three  or 
four  nasal,  and  two  small  palpebral  branches,  supplying 
in  turn  the  upper  lip,  side  of  the  nose,  and  the  lower  eye- 
lid. 

The  communications  of  these  branches  with  the  infra- 
orbital branch  of  the  facial  nerve  forms  the  infra-orbital 
plexus.     See  page  6i. 

Meckel's,  the  Sphenopalatine,  or  the  Nasal  Ganglion. 
Fig.  II. 

This  is  a  small  ganglion  placed  in  the  sphenomaxillary 
fossa  close  to  the  sphenopalatine  foramen  and  under  the 
superior  maxillar>^  nerve,  to  which  it  is  suspended  by  two 
sensory  branches  forming  its  sensor)'  root.  The  motor  and 
sympathetic  roots  enter  the  posterior  part  of  the  ganglion  as 
the  Vidian  nerv^e. 

The  Vidian  nerve  is  formed  by  the  junction  of  the  great 
superficial  petrosal  nerve  from  the  facial  with  the  great  deep 
petrosal  branch  from  the  sympathetic  plexus  on  the  carotid 
arter}-  in  the  carotid  canal.  The  united  nerv^es  pass  forward 
through  the  Vidian  canal  to  terminate  in  Meckel's  ganglion. 
Brandies  of  the  ganglion. 

(i)  Ascending  or  orbital  branches.  Three  or  more  very 
small  filaments  which  pass  to  the  orbit  through  the  spheno- 
maxillary'- fissure  and  supply  the  periosteum  and  mucous 
membrane  of  the  posterior  ethmoidal  and  sphenoidal 
sinuses. 

(2)  Descending  branches.  {a)  The  large  or  anterior 
palatine  nerve.  Passes  through  the  posterior  palatine 
canal  to  the  roof  of  the  mouth,  which  it  supplies  as  far 
forward  as  the  incisor  teeth.  This  nerve  gives  off  two  in- 
ferior nasal  filaments  while  in  the  posterior  palatine  canal, 
which  pass  forward  through  minute  openings  to  supply  the 


152  A  MANUAL   OF  ANATOMY. 

mucous  membrane  of  the  middle  and  inferior  meatuses 
and  inferior  turbinated  bone  of  the  nose.  {U)  The  small 
or  posterior  palatine  nerve  traverses  the  lesser  or  accessory 
palatine  canal  to  reach  and  supply  the  soft  palate,  the 
tonsil  and  the  uvula  ;  also  the  levator  palati  and  the  azygos 
uvulae  muscles,  {c)  The  external  palatine  nerve.  A  very 
small  filament  extends  through  the  external  palatine  canal 
to  supply  the  tonsil  and  the  soft  palate. 

(3)  The  internal  branches.  {a)  The  superior  nasal 
branches,  six  or  seven  filaments,  passing  through  the 
sphenopalatine  foramen  to  supply  the  mucous  membrane 
covering  the  posterior  part  of  the  middle  and  superior  tur- 
binated bones  and  the  posterior  ethmoidal  cells,  {b)  The 
septal  branch — nasopalatine,  "or  nerve  of  Cotunnius — 
crosses  the  roof  of  the  nose  to  the  septum,  runs  down- 
ward and  forward  buried  in  the  mucous  membrane  of  the 
septum,  which  it  supplies,  to  terminate  after  passing 
through  the  anteroposterior  pair  of  foramina  (Scarpa's) 
in  the  mucous  membrane  of  the  roof  of  the  mouth.  (The 
left  nerve  takes  the  anterior,  the  right  the  posterior 
foramen.) 

(4)  The  posterior  branch  has  already  been  described  as 
the  Vidian  nerve.     See  above. 


THE  BRAIN. 

The  Membranes  of  the  Brain. 

The  membranes  of  the  brain  are  the  dura,  arachnoid, 
and  the  pia. 

The  dura  has  already  been  described.      See  page  32. 

The  Subdural  Space. — The  space  between  the  dura 
and  the  following  membrane — the  arachnoid — is  called  the 
subdural  space. 


Fig.  20.    Base  of  the  Brain  Immediately  After  Removal  from  Skull.    [The 
slightly  hazy  appearance  is  due  to  the  presence  of  the  arachnoid  membrane.] 

1,  Optic  nerve. 

2,  Pituitary  gland,  which  rests  upon  (as  the  brain  lies  base  upward)  the  anterior  sub- 
arachnoidean  space. 

3,  The  posterior  subarachnoidean  space.     For  the  arteries  and  nerves  consult  the 
following  figures. 


154  A  MANUAL   OF  ANATOMY. 

The  Arachnoid  Membrane.     Fig.  20. 

This  is  a  very  thin  but  distinct  membrane  which  lies 
within  the  dura  and  in  turn  covers  the  pia.  It  is  connected 
to  the  latter  by  delicate  filaments,  especially  over  the  con- 
vexity of  the  brain,  called  the  subarachnoid  tissue,  hence 
it  is  sometimes  described  as  a  part  of  that  membrane  (pia). 

The  arachnoid  passes  smoothly  over  the  surface  of  the 
pia  and  does  not  follow  it  into  the  sulci  and  fissures,  except 
into  the  great  longitudinal  fissure,  in  order  to  get  from  one 
side  to  the  other  beneath  the  falx  cerebri ;  and  into  the 
great  transverse  fissure,  where  it  has  to  turn  around  the 
tentorium  cerebelli. 

Over  the  convexity  of  the  brain  the  arachnoid  lies 
closely  applied  to  the  pia  so  that  it  can  with  difficulty  be 
separated  from  it  and  demonstrated,  but  on  the  lower  sur- 
face (base)  of  the  brain  it  is  much  thickened  and  is  sepa- 
rated from  the  pia  in  two  well-marked  localities. 

These  spaces  within  the  arachnoid,  between  the  arachnoid 
and  the  pia,  are  called  the  subarachnoidean  spaces,  anterior 
and  posterior. 

(i)  The  anterior  subarachnoid  space  lies  at  the  base 
of  the  brain.  It  reaches  forward  to  the  beginning  of  the 
great  longitudinal  fissure,  laterally  to  the  inner  margins  of 
the  temporal  lobes  of  the  brain,  and  posteriorly  it  covers 
the  pons  and  medulla,  and  communicates  along  the  sides 
of  both  with  the  posterior  subarachnoid  space,  and  below 
with  the  similar  cavity  surrounding  the  spinal  cord. 

Within  the  anterior  subarachnoid  space  are  contained 
the  medulla,  the  pons  and  its  peduncles,  the  cerebral  crura, 
the  structures  at  the  base  of  the  brain  which  form  the 
floor  of  the  third  ventricle  (see  page  222),  the  basilar, 
internal  carotid  arteries,  and  their  branches,  especially  that 
arterial  anastomosis  which  forms  the  circle  of  Willis. 


THE  brain:  155 

(2)  The  posterior  subarachnoid  space  is  larger  than 
the  anterior.  It  is  formed  at  the  base  of  the  cerebellum 
by  the  arachnoid  membrane  which  extends  from  the  pos- 
terior part  of  the  cerebellum  to  the  upper  surface  of  the 
medulla.  It  communicates  with  the  spinal  arachnoid  space 
below,  with  the  anterior  subarachnoid  space  around  the 
sides  of  the  medulla,  and  with  the  interior  of  the  brain 
through  the  foramina  of  Majendie,  Key,  and,  Retzius. 

The  foramen  of  Majendie  is  centrally  located  in  the  pia 
which  reaches  from  the  under  surface  of  the  cerebellum 
to  the  upper  surface  of  the  medulla,  and  assists  in  forming 
the  roof  of  the  posterior  part  of  the  fourth  ventricle.  The 
opening  of  Majendie  is  found  close  to  the  medulla  and  in 
the  middle  line.  The  foramina  of  Key  and  Retzius  are 
minute  fissures  at  the  extension  of  the  pia  into  the  lateral 
angles  of  the  fourth  ventricle.  Other  smaller  and  less 
important  spaces  are  found  (3)  Below  the  falx  cerebri  and 
above  the  corpus  callosum,  in  the  great  longitudinal  fissure. 
(4)  In  the  fissure  of  Sylvius.  (5)  Between  the  corpora 
quadrigemina  and  the  anterior  extremity  of  the  cerebel- 
lum. 

The  Pacchionian  Glands,  Arachnoidal  Villi. — These 
are  up-growths  from  the  arachnoid  along  the  margins,  and 
even  into  the  cavity,  of  the  superior  longitudinal  sinus. 
They  look  Hke  small  masses  of  granulation  tissue.  They 
penetrate  the  dura  and  produce  corresponding  depressions 
in  the  inner  table  of  the  skull. 

The  subarachnoid  spaces  are  filled  with  a  lymphatic 
fluid  called  the  cerebrospinal  fluid.  This  fluid  is  able  to 
circulate  freely  from  the  cord  to  the  exterior  of  the  brain, 
and  even  to  the  interior  of  the  latter  through  the  foramina 
of  Majendie.  Key  and  Retzius.  Its  usual  quantity  is  about 
two  ounces. 


156  A  MANUAL  OF  ANATOMY. 

The  Function  of  the  Cerebrospinal  Fluid. 

It  forms  a  "water-bed  "  upon  which  the  brain  rests,  and 
is  thus  protected  from  injury  by  coming  in  contact  with  the 
projections  of  the  bones  forming  the  base  of  the  skull.  It 
equalizes  the  intracerebral  pressure,  by  flowing  away  from 
the  brain  when  the  blood  supply  is  too  great,  and  toward 
the  brain  when  it  is  insufficient. 

The  nerves  to  the  arachnoid  are  derived  from  the  fifth, 
seventh,  and  eleventh  cranial  nerves  (Bochdaleck).  The 
lymphatics  from  the  subarachnoid  spaces  (which  are  really 
lymph  channels)  communicate  with  those  of  the  internal  ear, 
mucous  membrane  of  the  nose,  and  the  superior  longitudi- 
nal sinus  ;  but  are  not  in  direct  communication  with  the 
general  lymphatic  system  of  the  head. 

The  subarachnoid  spaces  receive  the  lymphatics  from  the 
brain  (and  the  spinal  portion  from)  the  cord. 


DISSECTION. 

Carefully  remove  the  arachnoid  covering  in  the  anterior  and  posterior  sub- 
arachnoid spaces.  It  will  be  useless  to  attempt  to  remove  it  from  any  other 
part  of  the  brain. 

The  dissection  of  the  pia  consists  in  tracing  out  its  vessels.  This  should 
be  done  with  great  patience  ;   haste  means  destruction  of  important  parts. 

The  Pia.     Figs.  20  and  2 1 . 

This  is  the  most  internal  membrane  enveloping  the  brain. 
It  is  really  a  layer  of  blood-vessels  held  together  by  suf- 
ficient connective  tissue  to  preserve  their  relations,  which  is 
closely  applied  to  all  parts  of  the  outer  surface  of  the  brain, 
reaching  into  all  the  fissures  and  sulci,  and  even  passing  into 
the  interior  of  the  brain  as  the  velum  interpositum  and 
choroid  plexuses  of  the  lateral,  third,  and  fourth  ventricles. 
It  is  to  be  noted  that  these  extensions  from  the  general 
pia,  though  apparently  within  the  brain,  are  still  really  ex- 


Fig.  21.  The  Arterial  Supply  at  the  Base  of  the  Brain  (Circle  of  Wil- 
lis).— I,  Olfactory  nerve.  2,  Optic  nerve  and  chiasm.  3,  Infundibulum  torn  off  the 
tuber  cinereum.  4,  Corpora  albicantia.  5,  Fourth  nerve.  6,  Fifth  nerve.  7,  The 
sixth  nerve.  8,  Anterior  cerebral,  united  by  the  anterior  communicating.  9,  Internal 
carotid.  10,  Posterior  communicating.  11,  Third  nerve.  12,  Posterior  cerebral  artery. 
13,  Superior  (anterior)  cerebellar  artery.  14,  Basilar  artery.  15,  Inferior  (posterior) 
cerebellar  artery. 


158       •  A  MANUAL   OF  ANATOMY. 

eluded  from  the  central  cavities  of  the  brain,  as  will  appear 
later. 

The  Blood  Supply  of  the  Brain.     Figs.  lo  and  21. 

The  brain  receives  its  supply  of  blood  through  the  inter- 
nal carotids  and  vertebral  arteries. 

After  entering  the  skull  through  the  foramen  lacerum 
medium  the  internal  carotid  ai^tery  passes  forward  through 
the  cavernous  sinus  as  given  on  page  43.  At  the  anterior 
part  of  the  sinus  the  artery  turns  upward  through  the  dura, 
behind  and  internal  to  the  anterior  clinoidal  process,  and 
reaches  the  base  of  the  brain  at  the  beginning  of  the  fissure 
of  Sylvius,  where  it  divides  into  the  anterior  and  middle 
cerebral  vessels. 

The  vei'tebrals,  after  entering  the  skull  through  the 
foramen  magnum,  are  found  at  the  side  of  the  medulla. 
They  converge  as  they  pass  forward  and  unite  in  the  middle 
line  at  the  junction  of  the  pons  and  medulla  to  form  the 
basilar  artery. 

The  basilar  artery  runs  forward  in  a  median  depression  in 
the  pons  to  its  anterior  margin,  where  it  divides  into  the  two 
posterior  cerebral  vessels. 

The  Circle  of  "Willis.     Figs.  21  and  22. 

The  anterior  cerebral  arteries  pass  forward  and  inward 
to  the  beginning  of  the  great  longitudinal  fissure,  which 
they  enter.  They  continue  upward  and  backward  over  the 
corpus  callosum,  distributing  branches  to  the  inner  surface 
of  the  hemisphere  as  far  as  the  parieto-occipital  fissure 
(where  the  terminal  branches  anastomose  with  similar 
branches  from  the  posterior  cerebral  arteries). 

At  the  beginning  of  the  great  longitudinal  fissure  the 
anterior  cerebral  vessels  are  united  by  a  very  short  artery 


Fig.  22.  The  Circle  of  Willis,  Natural 
Size. — i,  Anterior  communicating.  2,  Anterior  cere- 
bral. 3,  Middle  cerebral.  4,  Internal  carotid.  5,  Pos- 
terior communicating.  6,  Posterior  cerebral.  7,  Supe- 
rior (anterior)  cerebellar.  8,  Basilar.  9,  Inferior  (pos- 
terior) cerebellar.     10,  Vertebral. 


159 


160 


A  MANUAL   OF  ANA  TO  MY. 


(shortest  in  the  body)  termed  the  anterior  communicat- 
ing-. 

For  the  branches  of  the  anterior  cerebral,  see  under  the 
ganglionic  and  cortical  systems. 

The  middle  cerebral  arteries  follow,  outward,  upward, 
and  then  backward  in  the  fissure  of  Sylvius,  and  near  its 
middle  part  divide  into  four  terminal  branches  ;  for  their 
course  and  distribution  see  Cortical  System. 


Diag.  lo.  A  Diagram  of  the  Ganglionic  Arterial  Supply  of  the  Brain. 
{Charcot,  from  Gray .) — i,  Anterior  communicating.  2,  Anterior  cerebral.  3,  Inter- 
nal carotid.  4,  Middle  cerebral.  5,  Posterior  communicating.  6,  Posterior  cerebral.  7, 
Basilar.  8,  Vertebral,  a,  Anteromedian  group,  b,  Anterolateral  group,  c.  Postero- 
median group,    d,  Posterolateral  group. 

The  posterior  cerebral  arteries  pass  outward  and  then 
backward  around  the  crura  cerebri  and  supply  the  inner 
and  under  surface  of  the  occipital  and  temporal  lobes. 

The  middle  and  posterior  cerebrals  are  joined  together 
in  front  of  the  crura  cerebri  by  the  posterior  commiTnicat- 
ing-  arteries.     These  are  usually  small  vessels  ;  one  may  be 


THE  BRAIN.  161 

very  small  or  wanting,  and  the  other  quite  large  to  make 
up  for  the  deficiency.  When  both  are  present  the  arterial 
circuit  called  the  circle  of  Willis  is  formed.  The  arteries 
which  form  it  are  the  two  anterior  cerebrals,  which  are 
united  by  the  anterior  communicating,  the  two  middle 
cerebrals  (or  internal  carotids),  which  are  joined  by  the  two 
posterior  communicating  vessels  to  the  two  posterior  cere- 
brals. Within  this  circle  are  found  the  following  structures 
at  the  base  of  the  brain.  The  posterior  perforated  space,  third 
and  fourth  nerves,  the  corpora  albicantia  or  mammillaria, 
the  tuber  cinereum,  infundibulum  and  pituitary  body,  the 
optic  chiasm  tracts  and  nerves,  and  the  lamina  cinerea. 

The  function  of  the  circle  of  Willis  is  to  maintain  an 
even  supply  of  blood  to  all  parts  of  the  brain.  The 
anastomoses  of  the  opposite  carotids  through  the  anterior 
cerebrals  and  anterior  communicating,  and  of  the  posterior 
cerebrals  with  each  other,  is  so  free  that  no  trouble  would 
arise  from  interference  with  one  carotid  or  one  vertebral. 

But  the  anastomosis  of  these  two  systems  through  the 
posterior  communicating  is  not  so  free  and  constant,  owing 
to  the  smallness  of  these  arteries,  or  even  the  absence 
of  one.  As  a  rule,  we  find  both  of  these  arteries  small, 
rarely  find  both  large,  often  one  may  be  quite  good  sized 
and  the  other  very  small  or  wanting  entirely.  In  cases 
where  there  is  not  a  free  communication  between  the 
anterior  and  posterior  parts  of  the  circle  of  Willis  it  would 
evidently  be  dangerous  to  ligate  both  carotids  at  one 
operation. 

The  cerebral  blood-supply  is  divided  into  the  vessels 
distributed  to  the  base  of  the  brain — ganglionic  system, — 
and  those  to  the  outer  surface  of  the  cortex — cortical 
system. 

The  blood  supply  to   the   brain   differs   from   the   blood 


162  A  MANUAL   OF  ANATOMY. 

distribution  in  other  parts  of  the  body  in    the   following 
points  : — 

(i)  The  main  arteries  do  not  divide  and  subdivide  and 
continue  to  do  so  until  the  arterial  capillaries  are  reached, 
but  each  trunk  gives  off  along  its  course  branches  which 
are  of  the  same  size,  and  the  trunk  ends  in  terminals 
which  are  of  the  same  size  as  the  branches.  (2)  The 
branches  from  the  ganglionic  system  do  not  anastomose 
with  each  other,  nor  do  the  branches  of  the  cortical  system, 
nor  do  the  branches  of  both  systems  anastomose  with 
each  other.  (3)  The  arteries  enter  the  brain  vertically  to 
its  surface,  and  proceed  inward  along  approximally  straight 
lines. 

The  G-anglionic  System.      Diag.  10.     Figs.  21,  22. 

This  system  embraces  all  the  branches  arising  from  the 
circle  of  Willis  and  an  inch  beyond  it.  The  branches  are 
arranged  in  four  groups  (two  being  double,  making  six 
really). 

(i)  The  anteromedian  group.  These  are  from  the 
anterior  cerebral  and  supply  the  anterior  part  of  the  cor- 
pus striatum.  (2)  (3)  The  anterolateral.  Branches  from 
the  middle  cerebral  to  the  corpus  striatum  and  anterior 
part  of  the  optic  thalamus.  These  branches  entering  the 
base  of  the  brain  produce  that  sieve-like  appearance  to 
which  the  name  of  "  perforated  "  space  (anterior)  is  given. 

The  lenticulostriate  artery  is  the  largest  and  most  im- 
portant branch  of  this  group,  because  it  is  most  frequently 
the  seat  of  hemorrhage  or  embolism.  Its  course  is 
upward  between  the  lenticular  nucleus  and  the  external 
capsule,  it  then  turns  inward  through  the  internal  capsule, 
and  terminates  in  the  caudate  nucleus. 

(4)  (5)  The  posterolateral  groups.      From  the  posterior 


THE  BRAIN.  163 

cerebrals  external  to  where  the  posterior  communicating 
enter,  supply  the  posterior  part  of  the  optic  thalamus, 
crura  cerebri,  and  the  corpora  quadrigemina.  (6)  The 
posteromedian  group.  Arise  from  the  posterior  communi- 
cating and  posterior  cerebrals,  enter  the  brain  (producing  the 
posterior  perforated  space),  and  supply  the  optic  thalami. 
Other  branches  not  supplying  the  basal  ganglia  : — 
(i)  The  anterior  choroid,  a  small  branch  from  the  back 
part  of  the  internal  carotid  or  the  middle  cerebral,  runs  back- 
ward, enters  the  lower  part  of  the  middle  horn  of  the  lateral 
ventricle  through  the  transverse  fissure,  and  supplies  the 
choroid  plexuses  of  the  lateral  ventricle,  hippocampus  major, 
and  corpus  fimbriatum.  (2)  The  posterior  choroid,  from 
the  posterior  cerebral,  supplies  the  upper  part  of  the 
choroid  plexuses  of  the  lateral  ventricles. 

The  Cortical  System. 

(i)  The  anterior  cerebral  takes  a  course  forward  and  in- 
ward from  the  internal  carotid,  enters  the  great  longitudinal 
fissure,  through  which  it  passes  backward,  lying  close  to  the 
corpus  callosum,  as  far  as  the  parieto-occipital  fissure.  The 
anterior  cerebral  gives  off  three  sets  of  cortical  branches, 
which  supply  the  under,  inner,  and  outer  surface  (first  and 
part  of  the  second  frontal  convolutions)  of  the  frontal  lobe 
and  the  quadrate  convolution  of  the  parietal  lobe. 

(2)  The  middle  cerebral.  This  is  the  larger  artery,  into 
which  the  internal  carotid  bifurcates  at  the  inner  end  of  the 
fissure  of  Sylvius.  The  artery  passes  outward,  backward, 
and  upward  through  the  Sylvian  fissure,  until  opposite  the 
lower  end  of  the  fissure  of  Rolando,  where  it  divides  into 
four  branches,  which  supply  the  greater  part  of  the  outer 
surface  of  the  cerebrum. 

The  ganglionic  branches  of  the  middle  cerebral  are  of  the 


164  A   MANUAL   OF  ANATOMY. 

utmost  importance,  especially  the  lenticulostriate  artery. 
For  these  see  above. 

The  cortical  arteries  are  distributed  as  follows  : — 

{a)  The  first  supplies  the  inferior  frontal  convolution. 
This  is  called  Broca's  artery,  supplying  that  convolution. 
Its  obstruction  in  the  left  side  produces  degeneration 
of  the  inferior  frontal  convolution,  which  is  manifested  by 
disorders  of  speech,  {b)  The  second  supplies  the  lower 
two-thirds  of  the  ascending  frontal  convolution,  {c)  The 
third  is  distributed  to  the  ascending  parietal  convolution. 
{d^  The  fourth,  to  the  supramarginal,  angular,  and  first 
temporal  convolutions. 

(3)  The  posterior  cerebral.  After  giving  off  the  posterior 
lateral  ganglionic  arteries  the  posterior  cerebral  divides  into 
three  sets  of  branches,  which  are  distributed  to  the  under 
and  lower  part  of  the  temporal  lobe  and  the  lower,  inner, 
and  outer  surfaces  of  the  occipital  lobe. 

The  Branches  of  the  Basilar  Artery. — The  formation, 
course,  and  ending  of  the  basilar  are  given  on  page  158. 

{a)  The  transverse  branches  supply  the  pons.  {B)  One 
of  these  transverse  branches  follows  the  auditory  nerve  into 
the  internal  auditory  meatus  and  is  termed  the  auditory 
artery,  {c)  Another,  a  large  branch,  supplies  the  anterior 
part  of  the  under  surface  of  the  cerebellum,  and  is  called 
the  inferior  cerebellar  artery,  {d^  The  superior  cerebellar 
arises  near  the  end  of  the  basilar,  courses  backward  and  up- 
ward around  the  crus  cerebri  to  the  upper  surface  of  the 
cerebellum,  which  it  supplies,  also  small  branches  are  given 
to  the  pineal  gland,  velum  interpositum,  and  the  valve  of 
Vieussens. 


THE  BRAIN.  165 

The  Cerebral  Veins. 

These  are  grouped  into  cortical,  basilar,  and  ganglionic 
(deep  or  central). 

The  superior  cortical  veins  gather  the  blood  from  the 
outer  and  inner  surfaces  of  the  cerebral  hemispheres  and  ter- 
minate in  the  superior  longitudinal  sinus.  They  are  eight 
to  ten  in  number,  and  open  into  the  sinus  forward,  contrary 
to  the  direction  of  the  blood  stream,  which  is  backward. 

The  basilar  or  inferior  cortical  veins  collect  the  blood 
from  the  lower  and  under  surface  of  the  cerebrum  and 
empty  into  the  cavernous,  superior  petrosal,  and  lateral 
sinuses.  The  more  important  of  these  are  the  {ci)  middle 
cerebral  vein,  which  accompanies  the  middle  cerebral 
artery  and  empties  into  the  cavernous  sinus.  {U)  The 
great  anastomotic  vein  of  Trolard  (which  extends  from 
the  parietal  lobe  to  open  into  the  superior  petrosal  sinus. 
It  communicates  above  with  the  superior  cerebral  veins  and 
thus  forms  a  communication  between  the  superior  longitu- 
dinal sinus  and  those  at  the  base  of  the  skull),  and  (r)  the 
posterior  anastomosing-  vein  of  Labbe  (which  passes  from 
the  middle  cerebral  vein  to  the  lateral  sinus  over  the  outer 
part  of  the  temporal  lobe). 

The  central,  ganglionic,  deep  cerebral  veins  empty 
into  the  veins  of  Galen,  which  will  appear  when  dissecting 
the  interior  of  the  brain. 

DISSECTION. 

The  pia  and  its  numerous  vessels  are  to  be  removed  from  the  brain.  This 
must  be  undertaken  very  slowly.  It  is  best  to  begin  the  removal  from  the 
cortical  surface,  then  from  the  inner  surface,  and  finally  from  the  base.  Dur- 
ing this  dissection  it  is  well  to  place  the  brain  in  a  basin  of  water,  which 
partially  floats  it  and  preserves  its  contour. 

When  working  upon  the  inner  surface  of  a  hemisphere  do  not  separate  them 
too  widely,  or  the  corpus  callosum  will  be  torn  through.  Do  not  draw  the 
vessels  directly  upward,  but  at  right  angles  to  the  surface. 


166  A  MANUAL  OF  ANATOMY. 

At  the  base  exercise  the  greatest  caution,  so  as  to  leave  behind  the  cranial 
nerves  and  the  other  important  structures  there.  About  the  nerves  it  may  be 
well  to  leave  the  pia,  as  they  usually  are  torn  off  with  it. 

Anteriorly  the  lamina  cinerea  will  be  torn  through  if  any  force  is  attempted 
in  taking  up  the  pia.  Do  not  attempt  in  any  place  to  remove  the  blood-ves- 
sels entire,  but  with  the  scissors  clip  them  wherever  there  is  any  resistance 
and  turn  to  another  place  close  by  to  continue  their  removal. 

The  Brain.     Figs.  23,  29. 

The  brain  is  all  that  part  of  the  cerebrospinal  system 
contained  within  the  cranial  cavity.  It  varies  in  weight 
according  to  sex,  age,  race,  and  intelligence  (see  qualifica- 
tions later).  At  birth  the  brain  bears  a  larger  proportion  to 
the  body  weight  than  at  any  later  time  ;  it  is  for  males  as 
I  :  5.85,  and  for  females  as  i  :  6. 5.  The  brain  grows  very 
fast  up  to  the  seventh  year,  but  not  so  fast  as  the  body 
weight  increases,  the  ratio  being  brain  to  body  as  i  :  1 3  or 
14.  The  increase  is  more  slowly  up  to  the  twentieth  year, 
when  the  ratio  to  the  body  is  as  i  :  30.  From  thirty  to 
forty  the  brain  grows  very  slowly,  reaching  its  maximum 
weight  between  forty  and  fifty  years  of  age.  After  the 
maximum  is  reached  the  brain  begins  to  lose  weight  very 
slowly,  at  the  rate  of  about  an  ounce  for  every  ten  years  of 
life. 

The  ratio  of  the  cerebrum  to  the  cerebellum  is  8^ :  i 
for  males,  and  8^ :  i  for  females. 

Race. — The  largest  brains  belong  to  the  civilized  races, 
Europeans  (English,  Germans,  Scotch,  etc.)  and  the 
Chinese.  The  smallest  to  the  savage  races,  as  the  native 
Africans  and  Australians. 

Intelligence. — While  there  is  some  ratio  between  the 
degree  of  intelligence  and  the  brain  weight,  it  is  at  most 
very  unreliable  for  comparison  between  individuals  of  the 
same  race.  As  Dana  states  ("Text  Book  of  Nervous 
Diseases  "),  among  100  intelligent  persons  the  proportion  of 


n    ^ 
in    c 


-is 

re*  S    - 
—   —  ^ 


"  -  £. 
o   <   »* 


to 


3     tfl    - 


167 


168 


A  MANUAL   OF  ANA  TOMY. 


large  brains  would  be  as  i :  4,  while  among  ignorant  people 
the  ratio  of  large  brains  to  the  rest  would  be  as  i  :  20. 

The  Development  of  the  Brain. — In  order  to  understand 
the  relations  of  the  several  parts  of  the  brain  to  each  other 
it  is  very  necessary  that  the  changes  which  take  place 
during  the  process  of  development  should  be  rehearsed. 
The  following  is  only  the  briefest  summary  of  the  import- 


Diag.  II.  A  Diagram  of  the 
Primitive  Medullary  Groove. — (/. 
S.H.) 


Diag.  12.  The  Primitive  Me- 
dullary "Tube"  and  its  Divisions 
INTO  Cerebral  Vesicles.— (/.  6'. 
H.)    X,  The  lamina  terminalis. 


ant  changes  ;  many  steps  have  to  be  omitted  for  lack  of 
space.  The  student  is  referred  for  a  complete  treatise  on  the 
subject  to  Minot's  "  Embryology." 

The  cerebrospinal  system  is  developed  from  the  epiblastic 
(ectodermal)  layer  of  the  blastoderm,  and  its  first  appearance 
is  in  the  nature  of  a  gutter  along  the  blastoderm  formed  by 
the  heaping  up  of  the  cells. 


THE  BRAIN.  169 

This  heaping  up  of  cells  goes  on  ;  they  rise  higher  and 
higher  and  finally  coalesce  over  the  gutter,  converting  it 
now  into  a  tube.  During  this  time  the  anterior  half  of 
the  tube  spreads  laterally  and  so  becomes  larger  than  the 
posterior  portion.  The  dilated  portion  is  the  forerunner  of 
the  brain  (cerebrum,  cerebellum,  pons,  and  medulla),  while 
the  long,  slender  hinder  portion  eventually  forms  the  spinal 
cord. 

We  will  confine  these  remarks  to  the  anterior  portion  of 
the  primitive  cerebrospinal  tube. 

The  next  change  is  the  production  of  three  distinct  swell- 
ings in  the  brain  end  of  the  tube,  these  swellings  being  pro- 
duced by  the  dilatation  of  the  central  canal  (internally)  and 
the  heaping  up  of  cells  (externally)  opposite  the  dilatations. 
These  dilatations  are  called  vesicles,  and  are  distinguished 
as  anterior,  middle,  and  posterior. 

These  three  original  vesicles  are  next  increased  to  five 
by  an  outgrowth  from  the  anterior  vesicle  and  a  subdivision 
of  the  posterior. 

The  anterior  extension  enlarges  forward,  outward,  up- 
ward, and  backward  ;  the  outgrowth  from  the  posterior  vesi- 
cle takes  place  upward,  laterally,  and  backward. 

These  five  vesicles  are  now  named  the  forebrain,  inter- 
brain  (original  anterior  vesicle),  the  midbrain  (middle  vesi- 
cle), hindbrain,  and  the  afterbrain  (both  from  the  posterior 
vesicle).  From  these  vesicles  all  the  complex  structures  of 
the  fully  formed  brain  are  developed  by  a  process  of  thick- 
ening here  and  there,  thinning  in  other  places,  the  pushing 
out  of  portions  here,  the  invagination  there,  and  the  flexions 
or  bending  of  the  axis  of  the  vesicles  until  the  completed 
brain  is  the  result. 

The  central  canal  of  the  primitive  vesicles  in  the  adult 
brain  constitutes  the  various  ventricles. 


170 


A  MANUAL   OF  ANA  TOMY. 


The  five  vesicles  furnish  the  following  parts  of  the  adult 
brain  : — 

The  forebrain  gives  origin  to  the  cerebrum,  corpora 
striata,  olfactory  lobes  and  the  lamina  terminalis,  (the  ex- 
treme  anterior  part  of  the  interbrain,   which  lies  between 


Diag.  13.  A  Third  Stage  in  the  Development  of  the  Cerebral  Vesicles.  (Altered 
from  Huxley.)  Horizontal  Anteroposterior  Section,  "roof"  of  Cerebral 
Vesicles  Removed. — i,  Olfactory  bulb,  opening  into  2,  The  forebrain.  (Cerebrum.) 
3,  Interbrain.  (Optic  thalamus.)  4,  Midbrain.  (Corpora  quadrigemina.)  5,  Hindbrain. 
(Cerebellum.)  6,  Afterbrain.  (Medulla.)  7,  Pineal  gland  removed,  a,  Opening  from 
olfactory  bulb  into  forebrain  cavity.  The  letter  lies  in  the  future  lateral  ventricle,  b. 
Blind  pit  of  the  infundibulum.  c,  Beginning  of  corpus  striatum,  d.  Beginning  of  optic 
thalamus,  e.  Site  of  the  future  foramen  of  Monro,  connecting  the  cavity  of  the  fore- 
brain (lateral  ventricle)  with  the  cavity  of  the  interbrain  (the  third  ventricle),  f. 
Aqueduct  of  Sylvius.  (Cavity  of  the  midbrain.)  g,  Fourth  ventricle.  (Cavity  of  the 
hind  and  afterbrain.)    x.  Lamina  terminalis. 


and  connects  the  forebrain),  from  which  are  developed  the 
corpus  callosum,  septum  lucidum,  fornix,  and  anterior 
commissure.  The  cavity  within  the  forebrain  is  the  lateral 
ventricles. 


THE  BRAIN.  171 

The  interbrain  gives  origin  to  the  optic  thalami,  pineal 
gland,  infundibulum,  (part  of  the)  pituitary  body,  the  optic 
nerve  (primarily).  The  cavity  within  the  interbrain  remains 
as  the  third  ventricle.  It  is  joined  to  the  lateral  ventricles 
by  the  foramina  of  Monro,  which  are  the  remains  of  the 
comparatively  wide  openings  in  the  embryo,  that  connects 
the  fore  and  interbrain  cavities. 

The  midbrain  furnishes  the  crura  cerebri,  corpora  quad- 
rigemina,  secondary  portion  of  the  optic  nerve.  The  narrow 
canal  which  runs  through  it  is  the  aqueduct  of  Sylvius. 

The  hindbrain  forms  the  cerebellum,  valve  of  Vieussens, 
pons,  and  the  anterior  part  of  the  fourth  ventricle. 


Diag.  14.  Same  stage  as  the  preceding  diagram.  Vertical  Anteroposte- 
rior Section  of  the  Cerebral  Vesicles.— (il/orf//ferf  frotn  Huxley.)  i,  Olfactory 
bulb.  2,  Forebrain  roof,  or  pallium.  3,  Pineal  gland.  4,  Corpora  quadrigemina.  5, 
Cerebellum.  6,  Pons,  and  behind  it  the  medulla.  7,  Crus  cerebri.  8,  Pituitary  gland, 
a.  Opening  of  olfactory  bulb  into  forebrain  cavity,  b.  Infundibular  pit.  c.  Corpus 
striatum,  d,  Optic  thalamus.  <?,  Site  of  the  foramen  of  Monro.  /,  Aqueduct  of 
Sylvius,  g.  Fourth  ventricle,  h.  Portion  of  the  roof  that  will  be  involuted  in  front  of 
the  velum  interpositum  and  choroid  plexuses,    x,  Lamina  terminalis. 


The  afterbrain  expands  into  the  medulla.  From  it  arises 
the  auditory  nerve,  and  it  completes  the  posterior  part  of 
the  fourth  ventricle. 

To  follow  the  changes  a  little  more  in  detail  that  result 
in  producing  the  above  results  :  The  forebrain  enlarges 
rapidly  forward,  outward,   upward,  and   backward   until  it 


172 


A  MANUAL   OF  ANA  TOMY. 


covers  in  the  rest  of  the  brain.  From  the  anterior  inferior 
part  of  the  forebrain  extends  forward  a  narrow  prolonga- 
tion, whose  cavity  is  at  first  in  direct  communication  with 
the  cavity  of  the  forebrain.  This  prolongation  is  the 
olfactory  lobe.  Its  cavity  becomes  filled  up  during  develop- 
ment and  is  no  longer  found  in  the  adult.     From  the  floor 


Diag.  15.  A  Fourth  Stage  in  the  Development  of  the  Brain.  Vertical 
Anteroposterior  Section  at  one  side  of  the  Median  'Lvak.— [Mo dijied  from 
Edinger.)  i,  Olfactory  bulb,  central  cavity  obliterated.  2,  Forebrain.  (Cerebrum.) 
3,  Attenuated  roof  of  midbrain  involuted  into  the  cavity  of  the  cerebral  vesicles  in 
front  of  the  velum  interpositum.  4,  Pineal  gland.  5,  Corpora  quadrigemina.  6, 
Cerebellum.  7,  Attenuated  roof  of  afterbrain  which  becomes  involuted  into  the  cavity 
of  the  fourth  ventricle  in  front  of  its  choroid  plexus.  8,  Corpus  striatum.  The  figure 
is  placed  on  the  fibres  of  the  internal  capsule  which  are  beginning  to  be  developed. 
9,  Optic  thalamus.  10,  Crus  cerebri.  11,  Pons.  12,  Medulla,  a,  Lateral  ventricle,  b, 
Third  ventricle,  c,  Aqueduct  of  Sylvius,  d.  Fourth  ventricle,  e.  Central  canal  of 
spinal  cord.  _/",  Caudate,  and  g,  Lenticular  nuclei  of  the  corpus  striatum  beginning  to 
appear,    h,  Transverse  fibres  of  pons  developing. 


of  the  vesicles  opposite  to  and  behind  the  site  of  the  foramen 
of  Monro  there  takes  place  an  upgrowth  of  cells,  in  two 
elongated  masses,  which  overlap  each   other.     The  long 


THE  BRAIN.  173 

axis  of  these  masses  lies  anteroposteriorly.  The  most 
anterior  (and  external)  mass  of  cells  becomes  the  adult 
corpora  striata,  the  posterior  (and  internal)  mass,  the  optic 
thalami.  These  masses  are  at  first  separated  from  each 
other,  but  as  growth  goes  on  they  become  united  along 
their  opposing  surfaces.  Furthermore,  the  primitive  corpus 
striatum  is  separated  from  the  lateral  wall  of  the  brain 
vesicle,  but  as  development  proceeds  the  two  approach  and 
finally  fuse,  but  this  line  of  junction  is  always  a  weak  spot 
in  the  brain.  Along  this  line  of  junction  the  lenticulo- 
striate  arter}^  passes,  and  that  this  line  of  junction  is  a  weak 
spot  is  proven  by  the  fact  that  cerebral  hemorrhage  takes 
place  here  from  this  arter}^  more  often  than  at  any  other 
point.  The  effused  blood  separates  the  apparently  united 
corpus  striatum  from  the  vesicular  wall. 

The  fore  part  of  the  interbrain  which  unites  the  fore- 
brains  of  opposite  sides  is  called  the  lamina  terminalis.  By 
the  extension  of  this  backward  along  with  the  growth  of 
the  forebrain  and  by  the  development  in  it  of  fibres  which 
connect  the  forebrains,  the  great  median  commissure — 
corpus  callosum — is  formed. 

The  portion  of  the  lamina  beneath  the  corpus  callosum 
is  projected  backward  in  the  shape  of  cyUndrical  bundles 
of  fibres  which  are  called  the  fornix. 

Between  the  fornix  and  the  corpus  callosum  the  lamina 
terminalis  persists  as  a  triangular  shaped,  very  thin  layer 
of  brain  matter,  which  helps  to  separate  the  two  lateral  ven- 
tricles and  is  called  the  septum  lucidum  (pellucidum). 

Within  the  septum  lucidum  by  a  process  of  vacuolation 
a  cavity  is  formed  which  in  the  adult  is  called  the  fifth  v^en- 
tricle.  It  has  no  connection  with  the  other  ventricular 
cavities  of  the  brain  which  are  developed  from  the  original 
cerebrospinal  canal. 


174  A  MANUAL   OF  ANATOMY. 

(The  above  formation  of  the  fifth  ventricle  is  taken  from 
Minot's  "  Embryology,"  and  is  undoubtedly  the  correct 
view,  though  contrary  to  the  usual  teachings.) 

Within  the  lamina  terminalis,  below  the  septum  lucidum, 
and  in  front  of  the  anterior  part  of  the  fornix,  is  developed 


Diag.  i6.  Median  Vertical  Anteroposterior  Section,  at  same  stage  as  pre- 
ceding diagram,  to  illustrate  the  development  of  the  lamina  terminalis  into  the  corpus 
callosum,  septum  lucidum,  fornix,  and  the  anterior  commissure. — (/.  S.  H.)  i,  Corpus 
callosum.  2,  Septum  lucidum.  3,  Anterior  commissure.  4,  Fornix.  5,  Optic  chiasm. 
Remainder  of  parts  as  in  preceding  diagram. 

a  well-defined  band  of  fibres  which  serves  to  connect  the 
opposite  forebrains  and  is  called  the  anterior  commissure. 

The  flexures  of  the  cerebral  vesicles  take  place  early 
and  consist  of  a  "  head-bend  "  at  the  midbrain,  and  later  a 
"neck-bend"  at  the  junction  of  medulla  and  spinal  cord. 


THE  BRAIN.  175 

The  first  bend  is  the  most  extensive,  the  axis  of  the  vesicles 
being  bent  to  a  right  angle.  These  bends  have  been  and 
will  be  disregarded  in  the  descriptions,  as  they  would  serve 
to  confuse  the  reader. 

The  changes  in  the  interbrain  :  The  development  of  the 
optic  thalami  has  been  given  above.  The  floor  of  the 
vesicle  drops  downward  to  form  a  blind  tube — the  infundi- 
bulum  ;  the  end  of  the  infundibulum  becomes  enlarged,  and 
meets  an  upward  pouch  from  the  pharynx  of  the  foetus. 
This  pharyngeal  pouch  becomes  narrowed  at  its  neck  and 
finally  cut  off  from  the  pharyngeal  cavity  and  remains  at- 
tached to  the  infundibulum.  The  rounded  mass  thus  formed 
from  the  brain  v^esicle  and  the  primitive  phar),mx  is  the 
hypophysis  or  the  pituitary  body.  The  cerebral  portion 
constitutes  a  small  central  mass  ensconced  within  the 
horseshoe  shaped  mass  from  the  pharynx.     Fig.  20. 

The  elevation  (depression,  really)  at  the  junction  of  the 
infundibulum  and  floor  of  the  vesicle  is  the  tuber  cinereum. 

On  each  side  of  the  median  line  two  elevations  appear, 
which  are  the  corpora  albicantia.  Forward  from  the  tuber 
cinereum  the  lamina  terminalis  is  continuous  under  the 
name  of  the  lamina  cinerea. 

The  midbrain  :  The  floor  becomes  thickened  by  the 
downward  extension  of  fibres  from  the  greatly  enlarged 
forebrain  (cerebrum),  and  these  masses  of  fibres  are  called 
the  crura  cerebri.  The  roof  of  the  midbrain  becomes 
bunched  to  form  the  corpora  quadrigemina.  Its  central 
canal  is  the  aqueduct  of  Sylvius. 

The  hindbrain  :  It  expands  upward,  outward,  and  back- 
ward until  the  result  is  the  cerebellum,  while  its  thicken- 
ing in  front  and  below  by  numerous  transverse  fibres  forms 
the  pons. 

The  afterbrain':  In    like  manner  forms  the  medulla,  by 


176  A  MANUAL  OF  ANATOMY. 

the  development  of  a  great  mass  of  connecting  fibres,  which 
unite  the  cord  below  with  the  rest  of  the  cerebrospinal 
system  above. 

The  cavity  within  the  hind  and  the  afterbrains  dilates  to 
form  the  fourth  ventricle. 

The  Formation  of  Fissures. — As  the  forebrain  increases 
in  size  and  enlarges  upward  and  backward  there  is  left  be- 
tween the  two  halves  a  deep  fissure,  which  is  the  great 
longitudinal  fissure  of  the  adult.  As  the  forebrain  enlarges 
it  extends  backward,  so  as  to  overhang  the  rest  of  the  brain, 
and  the  interval  thus  left  between  the  forebrain  and  the 
other  parts  of  the  brain  becomes  the  transverse  fissure  (of 
Bichat)  in  the  adult. 

The  above  constitutes  one  method  of  formation  of  the 
fissures  of  the  brain. 

Another  method  is  by  the  involution  of  the  entire  thickness 
of  the  cerebral  surface  itself  To  this  second  classification 
belong  the  fissures  of  Sylvius,  parieto-occipital,  calcarine, 
and  hippocampal. 

A  third  class  of  fissures  is  formed  by  the  tmequal 
growth  of  the  outer  layers  of  the  cerebral  surface.  The 
most  important  one  of  these  is  called  the  fissure  of  Rolando. 
To  these  depressions  the  name  of  sulci  is  applied  in  dis- 
tinction to  those  grooves  formed  between  parts  of  the  brain, 
or  by  the  involution  of  the  entire  thickness  of  the  brain 
wall,  which  are  called  fissures. 

The  formation  of  the  fissure  of  Sylvius  is  taken  as  an 
example  of  the  method  by  which  the  second  class  of 
fissures  is  formed. 

At  the  second  month  the  foetal  brain  (forebrain)  pre- 
sents a  smooth  surface,  but  beginning  with  this  period 
•  there  appears  upon  the  middle  of  its  outer  lower  surface  a 
depression. 


THE  BRAIN.  177 

By  the  growth  of  the  brain  at  a  much  faster  rate  above 
and  below  this  depression  its  depth  is  increased,  and  as  the 
brain  becomes  larger  the  fissure  becomes  deeper  and  longer, 
extending  backward  (the  horizontal  limb)  with  the  backward 
prolongation  of  the  forebrain.  Thus  the  fissure  is  formed 
by  the  excessive  growth  of  parts  of  the  cerebrum  about  a 
veiy  slowly  growing  portion,  so  at  the  last  the  slowly  grow- 
ing portion  is  covered  in  by  the  more  rapidly  growing  por- 
tions, and  there  is  left  between  them  a  fissure  which  leads 
to  the  former  part  of  the  brain  (in  this  case  to  the  insula). 

As  an  example  of  the  third  class  of  depressions — sulci 
— we  will  consider  the  formation  of  the  fissure  or  sulcus  of 
Rolando. 

The  first  appearance  of  the  fissure  of  Rolando  is  between 
the  fifth  and  sixth  months,  and  it  is  produced  by  the  growth 
of  the  cortex  of  the  cerebrum  on  either  side  of  a  linear 
depression  at  a  faster  rate  than  the  cortex  grows  along  the 
line  of  the  depression  itself  The  result  is  to  form  a  deep 
fissure.  All  the  rest  of  the  third  class  of  sulci  are  formed 
in  this  manner — by  the  upgrowth  of  the  cortex  at  a  faster 
rate  along  certain  lines  than  along  other  lines,  these  up- 
growths being  called  convolutions  and  the  depressions  sulci. 

Tlie  Fonnatioii  of  the  Vchuii  Litcrpositum  and  the  Choroid 
Plexuses. — (Diags.  13  to  16.)  Go  back  to  the  time  when 
there  are  the  three  primary  vesicles  ;  cover  them  with  the 
vascular  membrane,  which  is  to  become  the  adult  pia.  Now 
remember  how  the  forebrain  grows  backward,  taking  with 
it  the  lamina  terminalis  (corpus  callosum),  so  as  to  cover  in 
the  middle  vesicle.  The  forebrain  does  cover  in  the  middle 
vesicle  or  that  portion  of  it  which  we  call  its  roof,  but  upon 
this  roof  rests  the  vascular  membrane  (which  later  we 
designate  as  the  velum  interpositum),  so  at  the  end  of  the 
process  the  velum  interpositum  is  found   within  the  brain, 


178  A  MANUAL  OF  ANATOMY. 

but  is  excluded  from  the  ve7itriadar  cavity  by  the  remains  of 
the  roof  of  the  middle  vesicle,  whicJi  persists  as  a  thin  layer 
of  epithelial  cells  lining  its  under  surface.  Further,  the 
lateral  margins  of  the  velum  become  converted  into  a 
plexus  of  capillary  vessels,  to  which  the  name  of  choroid 
plexus  is  given.  These  lie  within  the  hollow  of  the  lateral 
ventricles,  but  are  separated  from  them  by  the  continuation 
of  the  layer  of  epithelial  cells  which  lines  the  velum. 
These  cells  cover  in  all  the  extensions  of  the  capillary  loops. 

In  an  exactly  similar  manner  is  the  choroid  plexus  of 
the  fourth  ventricle  developed  from  the  portion  of  the 
primitive  vascular  membrane  which  covers  in  the  roof  of 
the  hinder  portion  of  this  ventricle.  At  the  adult  stage, 
after  the  cerebellum  has  been  formed,  this  vascular  layer 
reaches  from  the  under  surface  of  the  cerebellum  to  the 
upper  surface  of  the  medulla.  It  is  lined  throughout  its 
extent  by  the  attenuated  remains  of  the  original  roof  of 
this  third  cerebral  vesicle.  The  layer  of  cells  is  applied  to 
the  membrane  so  as  to  cover  in  completely  (exceptions 
below)  all  the  festoons  of  capillaries  which  have  been 
formed  from  it. 

Remember  that  this  portion  of  the  roof  of  the  fourth 
ventricle  is  perforated  by  the  foramen  of  Majendie  close  to 
the  medulla  and  in  the  middle  line,  and  by  the  foramina  of 
Key  and  Retzius  at  its  lateral  extensions. 

The  Cerebrum.     Figs.  24  to  28. 

The  cerebrum  consists  of  the  great  mass  of  the  brain 
situated  at  its  anterior  and  superior  part.  It  is  the  greatly 
overgrown  forebrain. 

Its  shape  is  ovoid,  flattened  below,  and  partially  divided 
in  two  symmetrical  parts  by  the  great  longitudinal  fissure. 
These  halves  are  called  hemispheres,  right  and  left. 


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180  A  MANUAL   OF  ANATOMY. 

Each  hemisphere  is  further  subdivided  into  lobes,  for 
convenience  of  reference,  by  the  fissures. 

The  fissures  of  the  brain  may  be  divided  into  three 
classes  : — 

(i)  The  fissure  between  the  halves  of  the  cerebrum,  and 
that  between  the  cerebrum  as  a  whole  and  the  rest  of  the 
brain.  To  this  class  belong  the  great  longitudinal  and 
transverse  fissures.  (2)  Fissures  entirely  within  the  cere- 
brum itself,  which  are  formed  by  the  involution  of  the  entire 
thickness  of  the  cerebral  wall.  These  are  the  primary 
fissures  and  comprise  the  Sylvian,  dentate  or  hippocampal, 
parieto-occipital,  calcarine,  and  collateral  fissures.  Cor- 
responding to  the  external  depressions  of  the  primary  fis- 
sures are  internal  elevations  within  the  lateral  ventricles  of 
the  cerebrum.  (3)  Fissures  within  the  cerebrum,  which  are 
formed  by  the  upgrowth  of  the  outer  layer  (cortex)  of  the 
cerebrum  along  certain  lines,  depressions  being  left  between 
these  ridges.  The  ridges  are  called  convolutions,  the  depres- 
sions fissures  and  sulci.  (The  former  term  being  restricted 
to  the  deeper  and  earlier  appearing  depressions  of  this  class). 
These  constitute  the  secondary  fissures  (and  sulci)  and  are 
the  Rolandic  and  callosomarginal  fissures  and  all  the  re- 
maining sulci  of  the  cerebrum. 

The  Fissure  of  Sylvius.     Figs,  i,  7,  23,  24,  25,  28. 

The  Sylvian  fissure,  though  strictly  a  primary  fissure, 
belongs  to  the  class  of  fissures  formed  by  the  outgrowth  of 
the  cortical  wall  rather  than  by  an  involution  of  the  entire 
thickness  of  the  cerebral  wall. 

It  appears  during  the  third  month  of  development,  oppo- 
site the  floor  of  the  interbrain,  where  the  mass  of  cells 
which  is  to  form  the  corpus  striatum  is  found. 

Its  shape  is  first  triangular,  and  at  the  bottom  of  the  tri- 


;:  H 


JO  1) 

2   « 


c   _ 
o 


182  A   MANUAL    OF  ANATOMY. 

angle  lies  the  portion  of  the  cortex  which  is  external  to 
the  corpus  striatum.  As  growth  proceeds  and  the 
cortex  above  and  below  overlaps  more  and  more  the 
central  depressed  portion,  the  fissure  assumes  a  linear 
appearance. 

This  is  the  horizontal  limb  of  the  adult  fissure.  About 
the  fifth  month  an  offset  from  the  main  fissure  appears  ;  this 
ultimately  becomes  the  vertical  limb  of  the  adult  fissure. 

In  the  adult  the  fissure  of  Sylvius  begins  at  the  base  of 
the  brain  at  the  outer  part  of  a  perforated  layer  (anterior 
perforated  space),  passes  outward,  backward,  and  slightly 
upward  until  near  its  terminus,  when  it  turns  abruptly  up- 
ward to  end  in  the  parietal  lobe.  This  is  the  main,  or 
horizontal  limb  of  the  fissure.     Fig.  24. 

From  the  anterior  part  of  the  horizontal  limb  a  short  (one 
inch  long)  fissure  extends  forward  and  upward  into  the 
frontal  lobe  ;  this  is  the  ascending  or  vertical  limb  of  the 
fissure  of  Sylvius.  Sometimes  this  fissure  is  bifid  and  one 
part  extends  directly  forward  for  a  short  distance  into  the 
frontal  lobe,  forming  the  anterior  limb  of  the  fissure  of 
Sylvius. 

The  fissure  of  Sylvius  serves  to  separate  the  frontal  and 
parietal  lobes  above  from  the  temporal  lobe  below. 

The  Fissure  of  Rolando.      Figs,  i,  7,  23,  24,  26. 

This  fissure  appears  between  the  fifth  and  sixth  months  of 
foetal  development.  It  belongs  to  the  class  of  fissures  which 
are  formed  by  the  heaping  up  of  the  cortical  portion  of 
the  cerebrum  itself.  It  is  found  grooving  the  outer  surface 
of  the  cerebrum  about  at  its  middle.  Its  course  is  down- 
ward and  forward  from  about  the  middle  of  the  great  lon- 
gitudinal fissure,  into  which  it  frequently  opens,  to  near 
the  horizontal  limb  of  the  fissure  of  Sylvius.      It  forms  an 


Fig.  26.  The  Upper  Surface  of  the  Cerebrum  (same  brain  as  No.  24).—!,  Great 
longitudinal  fissure.  Divides  the  cerebrum  into  its  two  hemispheres.  2,  Fissure  of  Rolando. 
The  genua  are  very  distinct.  In  this  subject  the  fissure  extends  through  into  the  great 
longitudinal  fissure.  Cunningham  states  this  is  the  more  usual  condition.  3,  Parieto- 
occipital. The  external  portion  of  the  fissure  is  unusually  long.  4,  Superior  frontal 
sulcus.  5,  5,  The  praecentral  sulcus.  6,  hUraparietal  sulcus,  a.  Superior,  b,  middle 
and  c,  ascending  frontal  convolutions,  d,  Ascending  parietal  convolution,  e,  e,  Para- 
central convolution.  Consult  the  following  figure.  J',  Superior  parietal  convolution. 
f',  Superior,  h,  middle,  and  ;',  inferior  occipital  convolutions.  /,  Supramarginal  convo- 
ution.    k,  Angular  convolution. 


184  A  MANUAL   OF  ANATOMY. 

angle,  opening  forward,  of  about  Ji  degrees,  with  the 
longitudinal  fissure. 

The  course  of  the  fissure  is  not  perfectly  straight  but 
winding,  and  may  be  divided  into  three  segments  or  thirds  ; 
these  segments  make  with  each  other  angles  or  bends 
(genua)  ;  the  angle  formed  between  the  upper  and  middle 
thirds  points  backward,  that  formed  by  the  middle  and 
lower  thirds  points  forward  (superior  and  inferior  genu). 
Fig.  26. 

The  fissure  of  Rolando  separates  the  frontal  (anterior) 
from  the  parietal  (posterior)  lobe. 

The  Parieto-occipital  Fissure.      Figs.  26,  27. 

As  this  shows  only  slightly  upon  the  outer  surface  of 
the  cerebrum  its  description  will  be  omitted  until  the  inner 
surface  of  a  hemisphere  is  described.  Suffice  to  say  that 
its  external  portion  is  very  short  (one-half  of  an  inch)  and 
is  found  midway  between  the  fissure  of  Rolando  and  the 
apex  of  the  hemisphere  behind,  and  partially  divides  the 
parietal  from  the  occipital  lobe. 

The  Frontal  Lobe.      Figs.  23,  24,  26. 

The  frontal  lobe  is  situated  at  the  anterior  part  of  the 
cerebrum.  It  was  thought  to  correspond  to  the  limits  of 
the  frontal  bone — hence  its  name — but  such  is  not  the 
case,  as  the  lobe  reaches  backward  beneath  the  anterior 
third  of  the  parietal  bone. 

The  frontal  lobe  presents  three  surfaces,  the  external, 
internal,  and  inferior ;  these  are  also  called  the  frontal, 
mesial,  and  orbital.  The  external  surface  of  the  lobe  is 
cut  off  from  the  rest  of  the  cerebrum  by  the  fissure  of 
Rolando  behind  and  the  fissure  of  Sylvius  below.  The 
inferior  surface  rests  upon  the  orbital  plate  of  the  frontal 
bone.     The  internal  surface  is  separated  from  the  corres- 


THE  BRAIN.  185 

ponding  portion  of  the  opposite  lobe  by  the  falx  cerebri, 
and  is  marked  off  from  the  rest  of  the  internal  surface  by 
the  callosomarginal  fissure. 

The  frontal  lobe  presents  three  well-marked  tertiary 
fissures  :  the  superior  and  inferior — or  first  and  second 
frontal  sulci — which  run  anteroposteriorly,  and  the  pre- 
central,  which  is  at  right  angles  to  the  above,  and  irregu- 
larly parallel  to  the  fissure  of  Rolando.  The  last  fissure 
is  usually  interrupted  in  its  course,  and  the  anteroposterior 
sulci  may  terminate  in  it ;   the  superior  usually  does. 

These  sulci  divide  the  frontal  lobe  into  four  convolu- 
tions :  The  ascending-  frontal,  which  lies  parallel  with  and 
in  front  of  the  fissure  of  Rolando,  and  is  limited  in  front 
by  the  precentral  fissure.  The  superior  frontal  convolu- 
tion, which  becomes  continuous  on  the  inner  surface  with  the 
marginal  convolution,  on  the  inferior  surface  with  the  inter- 
nal convolution,  and  behind  with  the  ascending  frontal  convo- 
lution. The  middle  frontal  convolution,  between  the 
superior  and  inferior  frontal  sulci,  is  extended  around  to  the 
inferior  surface  of  the  frontal  lobe,  and  backward  to  the  pre- 
central sulcus,  by  which  it  is  separated  from  the  ascending 
frontal  convolution.  On  the  under  surface  of  the  lobe  this 
convolution  merges  into  the  middle  or  the  anterior  convolu- 
tion. The  inferior  frontal  or  Broca's  convolution  is 
below  the  inferior  sulcus,  arches  over  the  vertical  limb  of 
the  Sylvian  fissure,  and  becomes  continuous  behind  with 
the  ascending  frontal,  and  on  the  under  surface  of  the  frontal 
lobe  with  the  posterior  orbital  convolutions.  This  convolu- 
tion is  deeply  indented  on  its  under  surface  by  the  vertical 
limb  of  the  fissure  of  Sylvius,  and  above  by  the  precentral 
sulcus. 

The  internal  and  inferior  surfaces  will  be  described  on 
pages  1 88  and  192. 


186  A  MANUAL  OF  ANATOMY. 

The  Parietal  Lobe.     Figs.  23,  24,  26. 

Anteriorly  the  parietal  lobe  is  limited  by  the  fissure  of 
Rolando,  posteriorly  by  the  external  portion  of  the  parieto- 
occipital fissure  and  a  line  extending  in  the  direction  of  that 
fissure,  below  by  the  horizontal  limb  of  the  fissure  of  Sylvius 
and  a  line  continuing  its  horizontal  direction  to  the  posterior 
boundary.  Internally,  the  parietal  lobe  merges  into  the 
quadrate  lobe.      For  its  boundaries  see  page  191. 

The  parietal  lobe  is  furrowed  by  a  single  (named)  fissure 
or  sulcus,  the  intraparietal. 

The  intraparietal  sulcus  is  usually  found  in  the  shape  of 
a  horizontal  T-shaped  groove,  the  cross-bar  of  the  T  being 
parallel  with  the  fissure  of  Rolando,  and  the  upright  arm 
with  the  great  longitudinal  fissure.  This  arm  is  usually 
prolonged  into  the  occipital  lobe,  where  it  serves  to  mark 
off  the  superior  from  the  middle  occipital  convolutions. 

Between  the  fissure  of  Rolando  and  the  transverse  arm 
of  the  T  is  the  ascending  parietal  convolution.  This 
convolution  is  usually  continuous  around  the  lower  end 
of  the  Rolandic  fissure  with  the  ascending  frontal  convo- 
lution. The  lower  ends  of  these  two  convolutions  together 
with  the  adjacent  portion  of  the  inferior  frontal  convolution 
are  called  the  operculum — or  roof — because  they  cover  in 
the  central  lobe  or  island  of  Reil. 

The  ascending  frontal  and  parietal  convolutions  are  also 
often  united  around  the  upper  end  of  the  fissure  of  Rolando 
by  the  paracentral  convolution. 

Above  the  upright  arm  of  the  T  lies  the  superior  parietal 
convolution,  which  is  merged  into  the  quadrate  lobe  on  the 
inner  surface  of  the  hemisphere,  and  below  this  arm  is  the 
inferior  parietal  convolution,  which  is  further  subdivided 
into  two  convolutions — the  anterior  one,  the  supramarg-i- 
nal,  which  arches  over  the  upturned  extremity  of  the  hori- 


THE  BRAIN.  187 

zontal  limb  of  the  fissure  of  Sylvius  and  is  continuous  with 
the  ascending  parietal  convolution,  and  a  posterior  portion, 
which  similarly  embraces  the  extreme  posterior  part  of  the 
first  temporal  sulcus,  and  is  called  the  angular  convolution. 

The  supramarginal  convolution  connects  the  ascending  pa- 
rietal with  the  first  temporal  and  the  angular  convolutions. 

The  angular  convolution  connects  the  first  and  second 
(superior  and  middle)  temporal  convolutions  with  each 
other  and  also  with  the  middle  occipital  convolution. 

The  Temporal  Lobe.      Figs.  23,  24,  25. 

This  is  composed  of  all  the  cerebrum  lying  below  the  fis- 
sure of  Sylvius.  It  rests  upon  the  middle  fossa  of  the  skull, 
and  posteriorly  becomes  insensibly  continuous  with  the 
occipital  lobe. 

The  external  surface  of  the  temporal  lobe  is  divided  by  the 
superior  or  parallel  and  middle  sulci  into  three  convolu- 
tions, the  superior  (first),  middle  (second),  and  inferior 
(third)  temporal  convolutions.  These  run  parallel  with  the 
fissure  of  Sylvius  and  behind  are  continuous  with  the  con- 
volutions of  the  parietal  and  occipital  lobes,  viz.  :  The 
superior  convolution  with  the  supramarginal  and  angular 
convolutions,  the  middle  temporal  with  the  middle  occipital, 
and  the  inferior  temporal  with  the  inferior  occipital  convo- 
lution. 

The  parallel  or  superior  temporal  sulcus  follows  the 
direction  of  the  Sylvian  fissure  and,  like  that  fissure,  turns 
upward  at  its  terminus.  Curving  over  the  upturned  ex- 
tremity of  this  sulcus  is  the  angular  convolution  of  the 
parietal  lobe. 

The  Central  Lobe,  or  the  Island  of  Reil.      Fig.  25. 

This  lobe  is  seen  only  after  separating  the  sides  of  the 
fissure  of  Sylvius.      It  is  the  portion  of  the  cerebrum  which 


188  A  MANUAL  OF  ANATOMY. 

is  opposite  and  external  to  the  corpus  striatum,  and  which, 
not  keeping  up  in  growth  with  the  adjoining  portions  of  the 
cortex  cerebri,  becomes  covered  in  by  those  portions.  The 
island  is  traversed  by  three  or  four  shallow  sulci  which 
radiate  from  the  anterior  portion  of  the  lobe  in  a  direction 
upward  and  backward.  One  of  these  fissures,  the  central 
sulcus,  is  deeper  than  the  others,  and  divides  the  lobe  into 
a  large  anterior  portion  and  a  smaller  posterior  part.  The 
island  is  surrounded  by  a  well-marked  depression,  the  cir- 
cular sulcus. 

The  Occipital  Lobe.      Figs.  23,  24,  26. 

This  constitutes  that  portion  of  the  cerebrum  posterior 
to  the  parieto-occipital  fissure,  and  the  prolongation  of  the 
course  of  this  fissure  across  the  external  surface  of  the 
cerebrum. 

The  sulci  and  fissures  are  usually  very  poorly  marked 
off. 

The  sulci  may  be  determined  as  follows  :  The  superior 
occipital  sulcus  is  the  posterior  extremity  of  the  intra- 
parietal  sulcus,  or  at  least  of  a  sulcus  continuing  the  direc- 
tion of  this  fissure  backward  ;  similarly  the  inferior  occipital 
sulcus  is  part  of,  or  a  backward  extension  of,  the  middle 
temporal  sulcus.  By  these  two  irregular  and  indistinct 
grooves  three  convolutions  are  determined,  the  superior, 
middle,  and  inferior,  or  the  first,  second,  and  third  occipital 
convolutions. 

The  superior  convolution  is  continued  into  the  cuneate 
convolution  on  the  internal  surface  of  the  occipital  lobe. 

The  Inner  or  Mesial  Surface  of  the  hemisphere  taken  as 
a  whole.     Figs.  27,  38. 
Upon  the   internal   surface  of  the  hemisphere  are  found 
four  of  the  primary  fissures   of   the   cerebrum,   viz.  :  The 


Fig.  27.  The  Inner  Surfaces  of  the  Cerebral  Hemispheres.  (Same  brain 
as  No.  23  j — I,  Callosoniarginal  fissure.  2,  Fissure  of  Rolando  terminating  in  the  longi- 
tudinal fissure.  3,  Subparietal  sulcus.  4,  Parieto-occipilal  fissure.  5,  5,  Cakarine  fis- 
sure. 6,  Fissure  of  the  corpus  callosum.  7,  Collateral  sulcus.  8,  Dentate  fissure.  9, 
Fissure  of  Sylvius.  Convolutions — a,  Marginal.  6,  Paracentral,  c,  yuadrate.  d, 
Cuneate.  e,  Lingulate  J',  f,  g.  Falciform  lobe  divided  into  two  (some  make  three) 
divisions.  J\  f.  Gyrus  fornicatus.  (Under  the  splcnium  of  the  corpus  callosum  is  the 
isthmus  or  the  gyrus  hippocampi),  g.  Gyrus  uncinatus.  h.  Genu.  /,  Body,  and  j, 
Splenium  of  the  corpus  callosum.  k,  Optic  thalamus.  The  crura  cerebri  are  divided 
close  under  the  optic  thalami. 


190  A  MANUAL  OF  ANATOMY. 

parieto-occipital,  calcarine,  hippocampal  or  dentate,  and  the 
collateral. 

The  parieto-occipital  fissure  deeply  grooves  the  inner 
surface  of  the  cerebrum  in  a  direction  downward  and 
forward,  starting  at  the  junction  of  the  posterior  one-fifth 
with  the  anterior  two-fifths  of  the  margin  (inner)  of  the 
hemisphere,  and  terminating  opposite  a  point  directly  below 
the  splenium  of  the  corpus  callosum. 

The  calcarine  fissure  begins  in  the  posterior  part  of 
the  occipital  lobe  and  passes  directly  forward  to  merge 
into  the  parieto-occipital  fissure  at  its  middle  point. 

The  corresponding  elevation  within  the  lateral  ventricle 
produced  by  the  calcarine  fissure  is  called  the  calcar,  or 
hippocampus  minor. 

The  Hippocampal  or  Dentate  Fissure.      Figs.  27,  28. 

This  is  a  groove  which  begins  just  below  the  hinder  end 
of  the  corpus  callosum  and  runs  forward  in  the  internal 
margin  of  the  temporal  lobe.  The  elevation  which  it  pro- 
duces in  the  middle  horn  of  the  lateral  ventricle  is  the 
hippocampus  major.  By  separating  the  lips  of  the  fissure 
the  floor  is  seen  to  have  a  transversely  striated  appearance, 
hence  the  name  of  dentate  fissure. 

The  Collateral  Fissure.     Fig.  28. 

This  fissure  extends  anteroposteriorly  from  the  temporal 
into  the  occipital  lobes. 

The  raised  portion  of  brain  matter  produced  by  this 
fissure  in  the  floor  of  the  (posterior  and  descending  horns 
of  the)  lateral  ventricle  is  called  the  eminentia  coUateralis. 

The  Callosomarginal  Fissure.     Figs.  27,  38. 

This  is  a  well-marked  sulcus  which  begins  beneath  the 
anterior  extremity  of  the  corpus  callosum,  turns  backward, 
conforming  to  the  curve  of  this   structure   until  over  its 


THE  BRAIN.  191 

posterior  extremity  (the  splenium),  where  it  turns  upward 
to  the  margin  of  the  hemisphere. 

In  front  of  the  fissure  of  Rolando  there  is  an  offset 
from  the  callosomarginal  sulcus  which  serves  to  bound 
anteriorly  the  paracentral  convolution.  Also,  the  direction 
of  the  main  part  of  the  sulcus  is  continued  posteriorly 
nearly  to  the  parieto-occipital  fissure  under  the  name  of  the 
subparietal  sulcus.  This  sulcus  is  often  not  distinctly 
marked. 

The  cur\^ed  portion  of  cerebral  matter  external  to  the 
callosomarginal  sulcus  belongs  to  the  frontal  lobe  and  is 
called  the  marg-inal  convolution.  As  above  stated,  the 
portion  of  the  marginal  lobe  which  connects  the  ascending 
frontal  and  parietal  convolutions  is  called  the  paracentral 
convolution. 

The  square-shaped  mass  between  the  upturned  extremity 
of  the  callosomarginal  sulcus  and  the  parieto-occipital 
fissure  is  the  quadrate  lobe,  or  convolution.  It  is  the 
internal  portion  of  the  parietal  lobe  and  is  limited  inferiorly 
by  the  subparietal  sulcus. 

Between  the  posterior  portion  of  the  parieto-occipital 
and  the  calcarine  fissures  is  the  triangular  or  wedge-shaped 
convolution — the  cuneus — which  is  the  internal  part  of  the 
occipital  lobe.  The  marginal,  quadrate,  and  cuneate  con- 
volutions form  the  outer  arch  of  the  internal  surface  of  the 
hemisphere. 

Internal  to  this  outer  arch  of  convolutions  is  a  second 
arch,  which  starts  beneath  the  anterior  extremity  of  the 
corpus  callosum,  curves  backward  over  that  structure,  being 
separated  from  it  by  the  callosal  sulcus,  then  turns  around 
the  hinder  extremity  of  the  corpus  callosum,  and  under  the 
name  of  the  uncinate  convolution  extends  forward  to  the 
end  of  the  temporal  lobe. 


192  A  MANUAL   OF  ANATOMY. 

The  first  part  of  this  arch  is  called  the  gyrus  fornicatus, 
the  second  part  the  uncinate  gyrus  ;  they  are  connected  hj 
a  narrowed  portion — the  isthmus — just  under  the  posterior 
part  of  the  corpus  callosum.  Together  these  convolu- 
tions, with  some  internal  parts,  as  the  septum  lucidum, 
fascia  dentata,  and  fornix,  constitute  the  falciform  or  limbic 
lobe. 

The  uncinate  convolution  is  the  anterior  part  of  the 
superior  occipitotemporal  convolution,  which  lies  between 
the  calcarine  and  the  collateral  fissures. 

The  posterior  part  of  this  convolution  is  also  called  the 
lingulate  convolution. 

External  to  the  collateral  fissure,  between  it  and  the 
inferior  temporal  sulcus,  is  the  inferior,  or  simply  the  oc- 
cipitotemporal, convolution.  Some  writers  call  the  por- 
tion of  the  falciform  lobe  which  lies  behind  and  below  the 
hinder  end  of  the  corpus  callosum  the  gyrus  hippocampi, 
restricting  the  uncinate  gyrus  to  the  anterior  part  of  the 
hook. 

The  dentate  convolution  will  be  seen  best  during  the  dis- 
section. This  is  the  thin  fold  which  passes  from  the  end 
of  the  corpus  callosum  to  the  apex  of  the  temporal  lobe. 
It  is  found  within  the  arch  of  the  uncinate  gyrus. 

The  Callosal  Sulcus.      Figs.  27,  38. 

This  is  the  groove  which  is  found  between  the  corpus 
callosum  and  the  gyrus  fornicatus. 

The  Base  of  the  Brain.      Figs.  28,  29. 

TJie  Sulci  and  Convolutions. — The  under  surface  of  the 
frontal  lobe  :  Here  are  found  two  shallow  sulci,  an  external 
one  shaped  something  like  the  letter  H  or  X.  This  is  the 
orbital  sulcus,  and  the  convolutions  formed  by  it  are  the 
internal,  anterior,  and  the  posterior  or  external. 


Fig.  28.  Base  of  Cerebrl'm. — i,  Olfactory  sulcus.  2,  Orbital  sulcus.  3,  Fissure 
of  Sylvius.  4,  4,  Inferior  temporal  sulcus.  5,  Collateral  fissure.  6,  Calcarine  fissure. 
7,  Parieto-occipital  fissure.  8,  Dentate  fissure.  9,  9,  Great  longitudinal  fissure,  a,  In- 
ternal frontal  convolution.  A,  Anterior  frontal  convolution,  c,  Posterior  frontal  convo- 
lution, d,  Uncinate  convolution.  <?,  f,  Inferior  temporal  (occipitotemporal)  convolution. 
y,  Lingulate  convolution.  £■,  Cuiieate  convolution,  h.  Olfactory  nerve  (tract).  ;',  An- 
terior perforated  space.  J,  Optic  commissure,  nerves  and  tracts,  k,  Infundibulum  torn 
away  from  the  tuber  cinereum.  /,  Corpora  albicantia.  ui.  Crura  cerebri  divided  close 
to  pons,     n.  Aqueduct  of  Sylvius. 


13 


194  A  MANUAL  OF  ANATOMY. 

The  internal  is  continuous  with  the  superior  frontal 
convolution,  the  anterior  with  the  middle  frontal,  and  the 
posterior  or  external  with  the  inferior  frontal  convolution. 

The  internal  convolution  is  grooved  by  the  olfactory 
sulcus,  within  which  rests  the  olfactory  nerve. 

The  under  surfaces  of  the  temporal  and  occipital  lobes 
should  be  taken  together,  as  there  is  no  hne  separating 
them. 

The  fissures  seen  here  are  portions  of  the  hipppcampa! 
or  dentate,  the  parieto-occipital,  the  calcarine,  the  collateral, 
and  the  inferior  temporal.  This  last  is  more  often  com- 
posed of  several  short,  indistinct  grooves,  which  extend 
anteroposteriorly  along  near  the  external  borders  of  the 
temporal  and  occipital  lobes.  External  to  the  inferior 
temporal  sulcus  is  the  inferior  temporal  convolution  (ante- 
riorly) and  the  inferior  occipital  (posteriorly).  Between 
the  above  sulcus  and  the  collateral  fissure  lies  the  inferior 
occipitotemporal,  or  simply  the  occipitotemporal  convolu- 
tion. Then  between  the  collateral  and  the  calcarine, 
fissures  is  the  superior  occipitotemporal  convolution, 
which,  as  explained  before,  is  described  under  the  names  of 
the  uncinate  gyrus  for  the  anterior  part,  and  the  Ungulate 
convolution  for  the  posterior  portion.  To  see  these  convo- 
lutions and  sulci  the  cerebellum  must  be  raised. 

The  cerebral  hemispheres  will  be  found  separated  ante- 
riorly and  posteriorly  by  'Cut.  great  longitudinal  fissure. 

By  raising  the  temporal  lobe  the  beginning  of  the  Sylvian 
fissure  is  found  :  it  starts  behind  the  frontal  lobe  in  a  de- 
pressed portion  of  the  base  of  the  brain  [anterior  perforated 
space). 

Projecting  backward  from  the  centre  of  the  base  of  the 
cerebrum,  between  the  temporal  lobes,  are  seen  the  two 
rounded  masses  of  fibres,  which  are   called  the  legs  of  the 


Fig.  29.  Base  of  the  Brain. — i,  Lamina  cinerea.  2,  Anterior  perforated  space. 
3,  Tuber  cinereum  and  point  where  the  infundibulum  was  torn  off.  4,  Corpus  albicans. 
5,  Posterior  perforated  space.  6,  Fourth  nerve  crossing  the  crus  cerebri.  7,  Pons,  line 
points  to  the  median  groove.  S.  Under  surface  of  the  quadrate  convolution  of  cerebel- 
lum. 9,  Foramen  caecum.  10.  Flocculus.  11,  Olivary  body.  12,  Anterior  median  fis- 
sure of  medulla.  13,  Amygdala.  14,  Biventral,  or  cuneate  lobe.  15,  Olfactory  nerve 
(tract  really).  16,  Optic  tract.  The  optic  commissure  and  nerves  are  shown.  17,  Third 
nerve  18,  Fifth  nerve.  19,  Sixth  nerve.  20,  Seventh  and  eighth  nerves.  The  former 
internal  to  the  latter  2r,  Hypoglossal  nerve.  22,  Glosso-pharyngeal  nerve.  23,  Ante- 
rior pyramid  of  medulla.  24,  Pneumogastric  nerve.  25,  Spinal  accessory  nerve. 
26,  Great  longitudinal  fissure.    27,  Fissure  of  Sylvius. 


196  A  MANUAL   OF  ANATOMY. 

brain,  or  the  crura  cerebri.  They  are  joined  together  at 
their  hne  of  contact  along  the  middle  line. 

A  short  distance  posteriorly  the  crura  are  crossed  by  the 
transverse  fibres  of  the  pons,  which  pass  across  the  crura 
to  connect  the  two  halves  of  the  cerebellum  and  form  its 
middle  peduncles. 

Along  the  middle  line  the  pons  is  marked  by  a  shallow 
groove  in  which  rests  the  basilar  artery.  (The  pons  really 
does  not  bear  upon  the  artery  at  all,  but  upon  the  cerebro- 
spinal fluid  within  the  subarachnoid  spaces,  which  form,  as 
stated,  a  "  water-bed"  for  its  support.) 

The  longitudinal  fibres  issue  from  the  posterior  part  of  the 
pons,  and  from  this  point  to  the  margin  of  the  foramen  mag- 
num constitute  the  medulla. 

A  full  description  of  these  structures  will  appear  later. 

TJie  Central  Parts  at  the  Base  of  the  Cerebrum. — Begin- 
ning in  front,  in  the  anterior  part  of  the  great  long-itudinal 
fissure  which  separates  the  frontal  lobes  the  under  surface 
of  the  anterior  part  of  the  corpus  callosum  will  be  seen 
{tJiis  is  the  rostrwii). 

The  extension  of  the  floor  of  the  cerebrum  backward  from 
the  corpus  callosum  to  the  crossing  of  the  optic  nerves  is  in 
the  shape  of  a  thin  lamella  of  grey  matter  called  the  lamina 
cinerea.  The  lamina  cinerea  becomes  continuous  lat- 
erally with  the  anterior  perforated  spaces,  and  posteriorly 
with  the  tuber  cinereum.  On  either  sides  of  the  lamina 
cinerea  and  in  the  angle  between  the  temporal  and  frontal 
lobes  are  the  anterior  perforated  spaces,  small  areas  of  the 
base,  where  the  small  arteries  of  the  anterolateral  gangli- 
onic systems  enter  the  corpus  striatum.  The  anterior  per- 
forated space  is  really  the  under  surface  of  the  lenticular 
nucleus  of  the  corpus  striatum. 

From  the  sides  of  the  corpus  callosum  a  narrow  band  of 


THE  BRAIN.  197 

white  fibres  extend  backward  and  outward  to  the  beginning 
of  the  fissure  of  Sylvius.  These  bands  are  called  the 
crura,  or  peduncles  of  the  corpus  callosum. 

The  anterior  perforated  spaces  are  limited  internally  by 
these  peduncles. 

The  beginning  of  the  fissure  of  Sylvius  is  at  the  outer 
margin  of  the  anterior  perforated  space,  and  separates  the 
temporal  from  the  frontal  and  central  lobes  of  the  cerebrum. 

The  junction  of  the  optic  nerves  is  called  the  optic 
chiasm  or  commissure.  This  junction  takes  place  in  the 
middle  line  and  in  front  of  the  terminus  of  the  crura  cerebri. 
Outward  and  forward  from  the  commissure  projects  the  optic 
nerves,  while  backward  and  outward  extend  the  optic 
tracts,  which  curve  around  the  outer  side  of  the  crura 
cerebri  and  disappear  between  them  and  the  inner  margin 
of  the  temporal  lobes. 

Behind  the  optic  chiasm  is  an  elevation  (really  depres- 
sion) of  the  floor  of  the  cerebrum  called  the  tuber  cine- 
reum..  The  tuber  cinereum  is  prolonged  (downward)  in 
the  shape  of  a  funnel-shaped  stalk,  the  infundibulum, 
upon  which  or  attached  to  which  is  the  pituitary  gland 
(providing  the  brain  has  been  carefully  removed).  The 
two  lobes  of  the  pituitary  body  can  be  determined — a 
small  central  posterior  one  situated  within  the  horse-shoe 
shaped  anterior  and  larger  one.     See  Development,  page  175. 

Immediately  posterior  to  the  tuber  cinereum  and  close  to 
the  middle  line  are  two  small  but  Avell-marked,  rounded 
nodules,  the  corpora  albicantia  (from  their  white  color)  or 
mammillaria  (from  their  resemblance  to  the  mammae). 

Between  the  corpora  mammillaria  and  the  pons,  and  within 
the  depression  between  the  crura  is  the  posterior  perfo- 
rated space  formed  by  the  arteries  of  the  posterior  median 
ganglionic  system. 


198  A  MANUAL  OF  ANATOMY. 

All  these  structures  are  located  in  the  area  contained 
between  the  temporal  lobes  laterally,  the  pons  posteriorly, 
and  the  frontal  lobes  anteriorly.  This  space  is  called  the 
interpeduncular  space.  Within  it  the  Circle  of  Willis  has 
already  been  found,  page  i6i. 

The  lamina  cinerea,  optic  chiasm,  tuber  cinereum,  infundi- 
bulum,  and  posterior  perforated  space  all  take  part  in  form- 
ing the  floor  of  the  third  ventricle  of  the  brain. 

The  Superficial  Origin  of  the  Cranial  Nerves. 
I.  The  Olfactory.     Figs.  21,  28,  29,  9,  13. 

The  olfactory  nerve,  as  described,  is  really  not  a  nerve 
but  an  aborted  offset  from  the  foetal  forebrain. 

Its  central  cavity,  which  is  at  first  in  communication  with 
the  cavity  of  the  forebrain,  becomes  obliterated  as  develop- 
ment proceeds.      Diag.  14. 

The  nerve  consists  of  four  portions  :  the  roots  (of  which 
there  are  three),  the  tract,  the  bulb,  and  the  olfactory  nerves 
proper.  The  three  roots  may  be  traced,  one  externally 
(which  passes  to  the  amygdaloid  nucleus  in  the  anterior 
part  of  the  roof  of  the  descending  horn  of  the  lateral  ven- 
tricle), a  middle  (which  terminates  by  connecting  with  the 
fibres  of  the  anterior  commissure  within  the  substance  of 
the  corpus  striatum),  and  the  internal  (which  passes  to  the 
anterior  part  of  the  gyrus  fornicatus). 

The  tract  is  a  slender,  triangular-shaped  bundle  which 
passes  forward  from  the  roots  and  terminates  in  an  expanded 
extremity — the  bulb.  Both  lie  within  the  olfactory  sulcus 
of  the  frontal  lobe. 

The  olfactory  bulb  rests  upon  the  cribriform  plate  of  the 
ethmoid  bone,  and  the  olfactory  nerves  proper  pass  down- 
ward through  the  foramina  in  that  plate  to  the  mucous 
membrane  of  the  nose. 


Fig-  30.    Horizontal  Section  of  Cerebrum.    Corpus  Callosum  and  Lat- 
eral Ventricles. 

a,  Corpus  callosum,  showing  the  longitudinal  and  transverse  striations. 

b,  Caudate  nucleus  and  anterior  horn  of  the  lateral  ventricle. 

c,  Taenia   semicircularis ;    groove   between   the   caudate   nucleus   and    the  optic 
thalamus. 

d,  Optic  thalamus. 

g.  Choroid  i)lexus  disappearing  into  the  middle  horn  (^)  of  the  lateral  ventricle, 
y,  Posterior  horn. 
h,  Hippocampus  minor. 


200  A  MANUAL  OF  ANA  TOMY. 

The  cortical  centre  of  smell  is  located  in  the  uncinate 
convolution,  hippocampus  major,  and  the  pes  hippocampi. 

2.  The    Optic   Nerve.      Figs.  21,  28,  29,   38,    53,    54,   10, 

II,  12. 

This  passes  forward  from  the  optic  commissure  or  chiasm 
to  enter  the  optic  foramen  in  company  with  the  ophthalmic 
artery,  the  latter  being  external  and  inferior  to  the  nerve. 
See  page  57. 

The  optic  chiasm  is  the  junction  of  the  two  optic  tracts  at 
the  middle  of  the  base  of  the  brain  ;  it  lies  in  front  of  the 
tuber  cinereum  and  rests  upon  the  optic  groove  of  the 
sphenoid  bone. 

The  optic  tracts  extend  backward  and  outward  from  the 
optic  chiasm,  winding  around  the  crura  cerebri  and  under 
cover  of  the  temporal  lobes.  At  a  later  stage  of  the  dis- 
section the  optic  tracts  will  be  found  to  arise  from  the 
external  geniculate  body,  the  pulvinar  of  the  optic  thala- 
mus, and  the  anterior  of  the  corpora  quadrigemina  (the  ex- 
ternal arm)  ;  and  from  the  internal  geniculate  body  and  the 
posterior  of  the  corpora  quadrigemina  (the  internal  root). 
The  cortical  centre  of  sight  is  in  the  cuneate  convolution 
of  the  occipital  lobe. 

3.  The  Motor  Oculi.      Figs.  21,  29,  38,  10,  ii. 

This  nerve  issues  from  the  inner  side  of  a  crus  cerebri, 
close  to  the  pons,  passes  forward  through  the  cavernous 
sinus,  and  leaves  the  skull  through  the  sphenoidal  fissure. 
See  page  57. 

(Its  deep  origin  is  from  a  nucleus  in  the  floor  of  the 
aqueduct  of  Sylvius,  and  its  cortical  representation  is  in  the 
convolutions  about  the  lower  extremity  of  the  fissure  of 
Rolando.) 


THE  BRAIN.  201 

4.  The  Trochlear.      Figs.  21,  29,  34,  10,  ii. 

This  is  found  curving  forward  around  the  outer  side  of 
the  crura  cerebri.  It  enters  the  cavernous  sinus  and  leaves 
the  skull  through  the  sphenoidal  fissure.  See  page  50. 
(The  deep  origin  of  the  nerv^e  is  from  a  nucleus  in  the  floor 
of  the  aqueduct  of  Sylvius  behind  the  third  nucleus.  The 
fibres  of  the  fourth  nerve  decussate  across  the  valve  of 
Vieussens,  then  proceed  on  their  way  around  the  crura 
cerebri.) 

5.  The  Trig-eminus.      Figs.  21,  29,  53,  10,  ii,  12. 

The  superficial  origin  of  this  ner\^e  is  from  the  side  of 
the  pons  in  two  bundles,  a  larger  anterior  (sensory)  and  a 
smaller  posterior  (motor).  These  bundles  pass  forward 
over  the  inner  end  of  the  petrous  portion  of  the  temporal 
bone,  and  upon  the  front  surface  of  the  petrous  bone  the 
sensory  root  terminates  in  the  Gasserian  ganglion  while  the 
motor  root  passes  beneath  the  ganglion  to  the  foramen 
ovale.     See  page  46. 

(The  deep  origin  of  the  fifth  nerve  is  from  three  sets  of 
nuclei ;  one  in  the  floor  of  the  aqueduct  of  Sylvius,  from 
which  comes  the  descending"  root ;  a  middle  from  the  floor 
of  the  fourth  ventricle,  from  which  arises  the  middle  root; 
and  a  third  nucleus  from  the  upper  part  of  the  cervical 
division  of  the  spinal  cord,  from  which  arises  the  ascending 
root.  The  descending  root  is  sensory  and  trophic,  the 
middle  motor  and  sensory,  and  the  ascending  sensory.) 

Ophthalmic  division  see  page  54.  Superior  maxillary  divi- 
sion see  page  149.     Inferior  maxillary  division  see  page  1 17. 

6.  The  Abducens.      Figs.  29,  10,  ii. 

The  superficial  origin  is  in  the  groove  between  the  pons 
and  medulla,  and  from  between  the  olivary'  body  and  the 
anterior  pyramids   of  the   latter.      The  nerve  continues  for- 


202  A  MANUAL  OF  ANATOMY. 

ward  through  the  cavernous  sinus  to  the  sphenoidal  fissure, 
through  which  it  passes.      See  pages  43,  46,  57. 

(The  deep  origin  of  the  nerve  is  fi-om  a  nucleus  in  the 
floor  of  the  fourth  ventricle.) 

7.  The  Facial  Nerve.     Figs.  29,  53,  10,  11,  12. 

The  facial  arises  from  the  groove  between  the  pons  and 
the  medulla  at  the  outer  side  of  the  olivary  body.  The 
nerve  enters  the  internal  auditory  meatus  with  the  eighth 
nerve,  traverses  the  Fallopian  canal,  and  emerges  at  the 
base  of  the  skull  through  the  stylomastoid  foramen.  See 
page  61. 

Shortly  after  entering  the  canal  the  nerve  is  sHghtly 
thickened  ;  this  is  called  the  geniculate  ganglion.  From 
this  ganglion  are  given  off  the  greater,  lesser,  and  external 
superficial  petrosal  nerves. 

The  great  superficial  petrosal  nerve  passes  through 
the  hiatus  Fallopii  and  then  runs  forward  and  inward  to 
the  foramen  lacerum  medium,  pierces  the  cartilage  which 
fills  in  this  opening,  joins  the  deep  petrosal  nerve,  and 
forms  the  Vidian  nerve.      See  page  151. 

The  lesser  superficial  petrosal  nerve  passes  through  a 
small  opening  external  to  the  hiatus  Fallopii,  runs  forward 
and  inward,  and  leaves  the  skull  through  the  foramen 
ovale  to  terminate  in  the  otic  ganglion.      Seepage  1 19. 

The  external  superficial  petrosal  nerve  traverses  a 
minute  hole  external  to  the  above-mentioned  foramina  and 
terminates  in  the  sympathetic  plexus  on  the  middle  menin- 
geal artery. 

Below  the  geniculate  ganglion  the  facial  nerve  gives  off 
the  following  minute  twigs  :  one  to  the  stapedius  muscle, 
another  communicating  with  the  pneumogastric,  and  a 
larger     branch — the     chorda     tympani — which     courses 


Fig.  31.     Horizontal  Section  of  Cerebrum.    Corpus  Callosum  Removeex 

a.  a.  Divided  extremities  of  corpus  callosum. 

b.  Septum  lucidum. 

c.  Choroid  plexus. 

d.  Posterior  pillar  of  fornix.     The  free  margin  of  this  is  called  the  fimbria. 

e.  Body  of  fornix  divided  along  its  attachment  to  the  under  surface  of  the  corpus 
callosum. 

X,  X,  Foramina  of  Monro.    Remaining  parts  same  as  in  preceding  figure. 


204  A  MANUAL   OF  ANATOMY. 

through  the  middle  ear  and  reaches  the  base  of  the  skull 
by  way  of  the  canal  of  Huguier.     See  page  1 18. 

(The  deep  origin  of  the  facial  nerve  is  from  a  nucleus  in 
the  floor  of  the  fourth  ventricle  opposite  the  lower  part  of 
the  pons  ;  its  cortical  area  is  in  the  lower  part  of  the  pre- 
central  convolution  of  the  frontal  lobe.) 

8.  The  Auditory  Nerve.     Figs.  29,  53,  10. 

This  arises  just  external  to  the  facial  at  the  posterior 
margin  of  the  pons.  Its  course  is  outward  to  the  internal 
auditory  meatus  along  with  that  nerve.  Besides  these  two 
nerves  the  auditory  vessels  traverse  this  foramen. 

The  distribution  of  the  auditory  nerve  is  in  two  portions  : 
one  to  the  cochlea,  utricle,  and  saccule  ;  the  other  to  the 
semicircular  canals.  (The  deep  origin  of  the  nerve  is  from 
three  nuclei  in  the  floor  of  the  fourth  ventricle,  and  the 
cortical  location  for  hearing  is  in  the  first  or  superior  tem- 
poral convolution.) 

9.  The  Glossopharyng-eal  Nerve.     Figs.  53,  10,  11. 
The  ninth,  tenth,  and  accessory  portion  of  the  eleventh 

nerves  arise  from  the  side  of  the  medulla,  in  the  groove  be- 
tween the  restiform  tract  behind  and  the  olivary  body  and 
the  lateral  tract  of  the  medulla  in  front. 

The  deep  origin  of  these  nerves  is  from  a  continuous 
nucleus  in  the  floor  of  the  posterior  part  of  the  fourth  ven- 
tricle and  adjacent  part  of  the  cord. 

The  ninth,  tenth,  and  the  eleventh  nerves  leave  the  skull 
through  the  central  compartment  of  the  jugular  foramen. 
See  page  98. 

There  are  two  ganglia  developed  upon  the  glossopha- 
ryngeal nerve  in  its  course  through  the  jugular  foramen — 
the  jugular  and  the  petrous. 


Fig.  32.  Horizontal  Section  of  Cerebrum.  Fornix  Removed. — a,  b.  Divided 
corpus  callosum.  c,  Fifth  ventricle,  d,  Right  side  of  the  septum  lucidum.  t\  Anterior 
pillar  of  fornix  descending  to  base  of  cerebrum.  /,  Velum  interposituni.  The  choroid 
plexuses  have  been  removed  with  the  section  of  the  cerebrutn.  Their  divided  extremities 
show  in  the  descending  horns  of  the  ventricle.  g.  Caudate  nucleus,  h.  Lenticular 
nucleus,  i.  Internal  capsule.  Note  that  the  caudate  and  lenticular  nuclei  are  continuous 
with  each  other  around  the  anterior  portion  of  the  internal  capsule.  7,  Optic  thalamus. 
k.  External  capsule.  /,  Posterior  pillar  of  fornix  and  fimbria,  w/,  Hippocampus  major. 
n,  Hippocampus  minor,  o,  Eminentia  collateralis.  p.  Anterior  horn.  g.  Middle  horn. 
r.  Posterior  horn  of  lateral  ventricle,  .f,  Within  the  fissure  of  Sylvius.  The  island  of 
Reil  and  its  convolutions,    x,  x.  Foramina  of  Monro. 


206  A  MANUAL  OF  ANA  TOMY. 

Within  the  skull  the  ninth  nerve  gives  off  minute  men- 
ingeal twigs  to  the  dura  and  arachnoid. 

Within  the  j  ugular  foramen  arises  from  the  petrous  gang- 
lion the  nerve  of  Jacobson,  (which  passes  to  the  tym- 
panum), communicating  branches  to  the  superior  cervical 
ganglion  of  the  sympathetic,  to  the  pneumogastric,  and  to 
the  lingual  branch  of  the  facial. 

10.  The  Pneumogastric  Nerve.     Figs.  53,  10,  11 
As  given  above  and  described  on  page  103. 

11.  The  Spinal  Accessory.      Figs.  53,  10,  ii. 

The  accessory  portion  has  been  given  with  the  glosso- 
pharyngeal ;  the  spinal  part  arises  from  the  anterolateral 
surface  of  the  cord  as  low  as  the  fifth  or  sixth  cervical  ver- 
tebra. These  filaments  pass  upward,  uniting  to  form  a 
single  trunk,  which  enters  the  skull  through  the  foramen 
magnum ;  then,  being  joined  by  the  accessory  portion,  the 
nerve  passes  out  from  the  skull  as  above  given  along  with 
the  ninth  and  tenth  nerves  through  the  central  division  of 
the  jugular  foramen.      See  page  91. 

12.  The  Hypoglossal  Nerve.      Figs.  53,  10,  II. 

The  superficial  origin  of  this  nerve  is  from  the  groove 
between  the  olivary  body  and  the  anterior  pyramids  of  the 
medulla.  The  nerve  is  in  the  shape  of  two  portions,  which 
do  not  become  joined  until  they  enter  the  anterior  condy- 
loid foramen,  through  which  the  nerve  leaves  the  skull. 
See  page  88. 

(Within  the  foramen  a  recurrent  meningeal  twig  is  given 
off  to  the  dura.) 

(The  deep  origin  of  the  nerve  is  from  a  long  nucleus 
internal  to  that  for  the  ninth,  tenth,  and  eleventh  nerves, 
close  to  and  parallel  with  the  median  line  in  the  floor  of 


THE  BRAIiY.  207 

the  fourth  ventricle.  The  cortical  area  for  the  nerve  is 
in  the  lower  part  of  the  convolutions  about  the  fissure  of 
Rolando.) 

DISSECTION. 

Separate  the  halves  of  the  cerebrum  and  examine  the  upper  surface  of  the 
corpus  callosum. 

With  a  long,  sharp  knife  slice  off  the  top  of  the  hemispheres,  about  half  an 
inch  above  the  corpus  callosum.  The  oval  section  presenting  is  called  the 
centrum  ovale  minus.  Its  surface  will  show  the  divided  vessels,  and  its  mar- 
gin the  arrangement  of  the  white  and  gray  matter.  The  formation  of  the 
convolutions  and  sulci  should  be  examined. 

Remove  a  slice  of  the  brain  on  a  level  with  the  corpus  callosum,  opening 
into  the  lateral  ventricles.  This  section  is  called  the  centrum  ovale  majus. 
Or  the  brain  matter  can  be  torn  from  the  fibres  of  the  corpus  callosum  on  one 
side,  showing  its  arched  formation  and  the  forceps  major  and  minor.  While 
on  the  other  side  the  brain  can  be  cut  away,  opening  into  the  lateral  ventricle. 

Consult  the  section,  Fig.  30,  which  shows  the  horns  of  that  ventricle, 
and  expose  them  in  the  specimen  in  a  similar  manner  on  this  one  side. 

The  Corpus  Callosum. 

The  form  of  the  great  central  commissure  which  joins 
the  two  halves  of  the  cerebrum  must  be  learned  from  trans- 
verse and  anteroposterior  sections  of  the  brain.  See  Figs. 
27,  30,  38,  45. 

The  corpus  callosum  is  composed  of  fibres  which  con- 
nect symmetrical  parts  of  the  opposite  hemispheres,  but 
these  fibres  being  restricted  to  the  central  portion  of  the 
opposing  surfaces  of  the  hemispheres,  they  become  crowded 
together,  more  at  the  anterior  and  posterior  extremities. 

On  cross  section  of  the  corpus  callosum,  this  bunching 
together  of  the  fibres  is  best  seen — and  the  result  is  to 
produce  a  thickening  at  these  points.  The  posterior  thick- 
ening is  called  the  spleniiini  and  the  anterior  the  gciiii  or 
knee,  because  here  the  fibres  of  the  corpus  turn  downward 
to  the  base  of  the  brain.  This  bend  constitutes  the  genu 
(knee),  and  the  lower  descending  limb  of  the  corpus  gradu- 


208  A  AIAA'^UAL  OF  ANATOMY. 

ally  becomes  thinner  and  is  termed  the  rostrum,  where  it 
passes  backward  into  the  lamina  cinerea.  The  part  of  the 
corpus  callosum  between  the  genu  and  splenium  is  the  body, 
and  is  thinner  than  those  parts. 

There  is  a  small  extension  of  the  corpus  callosum 
folded  beneath  the  splenium,  called  the  reduplicated  fold  of 
the  corpus  callosum.      Fig.  39. 

The  corpus  callosum  has  a  bow-shape  on  transverse 
section.  The  concave  extremities  of  the  bow  arch  over 
the  lateral  ventricles  (whose  roofs  they  form),  and  the 
central  depressed  portion  is  the  portion  of  the  corpus  cal- 
losum which  is  seen  on  separating  the  hemispheres. 

To  the  under  surface  of  the  corpus  callosum  is  found 
attached  (anteriorly)  the  septum  lucidum  and  (posteriorly) 
the  fornix.     Figs.  41  to  48  inclusive. 

Remember  that  these  three  structures  are  all  de- 
veloped from  the  fcetal  lamina  terminalis.  Page  173. 
Diag.  16. 

The  anterior  part  of  the  corpus  callosum  covers  in  the 
anterior  horn  and  body  of  the  lateral  ventricle,  while  the 
posterior  part  (the  tapctiiui)  forms,  in  a  like  manner,  the 
covering  for  the  descending  and  posterior  horns  of  the 
same  ventricle. 

The  bundles  of  fibres  which  radiate  to  the  frontal  lobe 
from  the  genu  are  called  the  forceps  minor,  while  the  bun- 
dles of  fibres  which  pass  from  the  splenium  and  the  redu- 
plicated fold  of  the  corpus  callosum  radiate  to  the  occipital 
lobe  and  constitute  the  forceps  major. 

As  stated,  the  corpus  callosum  is  made  up  of  transverse 
fibres,  with  the  exception  of  a  few  thin  bundles  of  fibres 
which  extend  from  the  anterior  part  of  the  base  of  the  brain 
to  the  forceps  major,  and  use  the  corpus  callosum  as  a 
bridge  for  their  course.     Fig.  30. 


F'g-  33-  Horizontal  Section  of  Cerebrum.  The  Internal  Capsule  and  Ad- 
joining Nuclei. — a,  Corpus  callosum.  d,  Septum  lucidum.  c,  Anterior  pillars  of  fornix. 
d,  Middle  commissure,  e,  Pineal  gland  and  posterior  commissure,  y",  Corpora  quadri- 
gemina.  ^,  Upper  surface  of  cerebellum.  A,  A,  Longitudinal  fissure.  /,  Caudate  nucleus. 
J,  External  capsule,  k,  Claustrum.  /,  Lenticular  nucleus.  Note  that  the  claustrum  and 
the  lenticular  nucleus  are  closely  approaching  each  other  at  their  posterior  portions. 
Deeper  down  they  become  continuous.  »i,  Anterior  limb,  n,  Knee,  and  o,  Posterior  limb 
of  the  internal  capsule,  p,  Optic  thalamus,  g,  Middle  horn,  containing  the  choroid 
plexus,  r,  Hippocampus  major,  s,  Anterior  horn,  t,  Third  ventricle.  .*■,  Foramen  of 
Monro.  The  base  of  it. 
14 


210  A  MANUAL   OF  ANATOMY. 

These  fibres  are  grouped  in  four  bundles,  one  beneath 
each  gyrus  fornicatus — tcenicB  tectce — and  one  on  either 
side  of  the  median  line — the  stricB  longitudinales  ;  between 
the  latter  a  thin  groove  is  left  called  the  raphe. 

The  longitudinal  fibres  start  from  the  base  of  the  brain, 
at  the  beginning  of  the  fissure  of  Sylvius,  and  pass  forward 
to  the  corpus  callosum  (as  its  peduncles),  over  which  they 
continue  to  the  forceps  major. 

The  taeniae  tectae  are  stray  fibres  belonging  to  the  gyrus 
fornicatus. 

The  Lateral  Ventricles.  Figs.  30,  31,  32,  35,  41  to  49 
inclusive. 

These  are  the  irregular  cavities  which  are  contained  with- 
in the  cerebral  hemispheres. 

Each  lateral  ventricle  communicates  with  the  third  ven- 
tricle and  with  each  other  through  the  foramina  of  Mon- 
ro. A  lateral  ventricle  presents,  in  horizontal  section,  a 
central  portion,  an  anterior,  a  posterior,  and  a  middle  pro- 
longation or  horn.  The  anterior  horn  curves  forward, 
downward,  and  outward,  the  posterior  hoini  curves  back- 
ward and  inward,  and  the  middle  horn  takes  a  course 
backward,  outward,  downward,  forward,  and  inward  (the 
descending  horn). 

All  these  prolongations  open  into  the  body  of  the  ven- 
tricle, which  is  that  portion  of  the  ventricle  extending  from 
the  foramen  of  Monro  to  the  beginning  of  the  descending 
and  posterior  horns,  and  corresponds  to  the  intraventricular 
portion  of  the  optic  thalamus. 

The  Boundaries  of  the  Ventricle. — The  anterior  horn, 
body,  and  posterior  horn  are  roofed  over  by  the  arched 
corpus  callosum  as  previously  described.  The  internal  wall 
of  the  anterior  horn  is  formed  by  the  septum  lucidum  ;  of 


f'S-  34-  Dissection  to  Show  the  Course  of  the  Anterior  Commissure. — 
a,  The  rostrum  of  corpus  callosum.  (See  Fig.  38.)  The  letter  lies  in  the  longitudinal  fissure. 
/>,  b.  Fibres  of  anterior  commissure.  Their  course  is  outward  from  the  middle  line,  then 
downward  and  backward  underneath  the  lenticular  nuclei  (which  have  been  removed)  to 
terminate  in  the  roof  of  the  middle  horn  of  the  lateral  ventricle,  c,  The  third  ventricle. 
d,  Internal  capsule,  now  the  crusta  of  crus  cerebri,  e,  Locus  niger.  /,  Red  nucleus,  g. 
Tegmentum,  h,  Aqueduct  of  Sylvius.  /,  Lingula  resting  upon  the  valve  of  V'ieussens. 
j,  Fourth  nerve. 


212  A  MANUAL   OF  ANATOMY. 

the  body,  by  the  posterior  part  of  the  septum  lucidum  and 
the  fornix ;  of  the  posterior  horn,  by  the  hippocampus 
minor  and  the  bulb  of  the  posterior  horn. 

The  hippocampus  minor  is  an  elevation  along  the  inner 
wall  of  the  posterior  horn,  formed  by  the  involution  of  the 
brain  corresponding  to  the  calcarine  fissure. 

The  bulb  of  the  posterior  horn  is  a  bulging  in  the  pos- 
terior horn  above  and  parallel  with  the  hippocampus  minor 
produced  by  the  bundle  of  fibres — the  forceps  major — which 
is  proceeding  from  the  splenium  of  the  corpus  callosum  to 
the  occipital  lobe.  The  floor  of  the  anterior  horn  and 
body  of  the  ventricle  present  from  before  backward  the 
caudate  nucleus  (the  intraventricular  portion  of  the  corpus 
striatum),  the  taenia  semicircularis,  the  optic  thalamus, 
choroid  plexus,  and  posterior  pillar  of  the  fornix. 

The  floor  of  the  posterior  horn  is  a  flat  surface  behind 
but  becomes  gradually  elevated  as  the  floor  passes  into  the 
descending  horn  ;  this  raise  is  the  eniinentia  collateralis,  and  is 
produced  by  the  upheaval  of  the  brain  over  the  collateral 
fissure. 

The  middle  or  descending  horn  of  the  lateral  ventricle  : 
The  course  of  this  extension  of  the  cavity  of  the  lateral 
ventricle  is  backward,  outward,  and  downward,  then  forward, 
downward,  and  inward  to  the  anterior  extremity  of  the 
temporal  lobe. 

The  roof  of  the  horn  is  formed  by  that  portion  of  the 
body  of  the  corpus  callosum  passing  to  the  temporal  lobe 
and  is  called  the  tapetum,  also  by  the  tail  of  the  caudate 
nucleus  and  the  taenia  semicircularis.  At  the  extreme 
anterior  portion  the  roof  is  formed  by  the  amygdaloid 
nucleus  in  which  the  tail  of  the  caudate  nucleus  and  the 
taenia  semicircularis  terminate.      Figs.  36,  37. 

The  inner  wall  presents  a  long,  rounded  eminence — the 


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214  A  MANUAL   OF  ANATOMY. 

hippocampus  major — the  posterior  pillar  of  the  fornix, 
the  fimbria  (the  free  edge  of  this  portion  of  the  fornix),  and 
the  choroid  plexus. 

The  floor  is  taken  up  by  the  eminentia  collateralis. 

The  hippocampus  major  is  an  elongated  roll  of  brain 
matter  along  the  inner  wall  of  the  descending  horn  of  the 
lateral  ventricle,  which  is  produced  by  the  outward  involu- 
tion of  the  cerebral  cortex  of  the  temporal  lobe  to  accom- 
modate the  hippocampal  or  dentate  fissure.  Figs.  35,  45, 
46,  47. 

The  hippocampus  major  terminates  at  the  anterior 
extremity  of  the  descending  horn  in  a  broadened  indented 
end  which  resembles  (slightly)  the  paw  of  an  animal — 
hence  the  name  of  pes  liippocanipi. 

DISSECTION. 
Remove  the  corpus  callosum,  exposing  both  lateral  ventricles.     Trace  the 
descending  horn   on  one  side   by  cutting    the  brain   away  from   the   outside. 
Save  the  septum  lucidum  (between  the  halves  of  which  find  the  fifth  ventricle) 
and  the  fornix. 

The  Septum  Lucidum,  Figs.  31,  32,  33,  38,  39,  41  to 
44  inclusive. 

This  will  be  seen  on  transverse  sections  to  be  a  thin, 
double  layer,  and  on  anteroposterior  sections  to  have  a 
triangular  shape  and  to  be  attached  in  front  and  above  to 
the  inner  surface  of  the  corpus  callosum,  and  below  and 
behind  to  the  fornix. 

It  is  described  as  the  attenuated  wall  of  the  hemispheres, 
which  was  imprisoned  within  the  brain  by  the  development 
of  the  fibres  of  the  corpus  callosum  above  it.  But  such  is 
not  its  derivation,  for  it  is  a  thinned  and  broadened  lamina- 
tion of  the  central  portion  of  the  lamina  terminaHs,  from 
which  it  comes,  the  outer  portion  of  the  lamina  terminalis 
being  developed   into  the   corpus   callosum  and   the  inner 


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216  A  MANUAL  OF  ANATOMY. 

portion  into  the  fornix.  See  Development,  page  173  and 
Diag.  16. 

The  septum  lucidum  consists  of  a  double  layer  for  some 
extent ;  the  small,  oval,  slit-like  cavity  between  the  two  layers 
is  the  fifth  ventricle.  This  ventricle  is  not,  in  all  probability, 
a  portion  of  the  foetal  longitudinal  fissure  which  has  become 
included  beneath  the  corpus  callosum,  but  is  formed  within 
the  originally  solid  septum  lucidum  by  a  process  of  vacuola- 
tion. 

The  fifth  ventricle  has  no  communication  with,  nor  is  it 
formed  in  any  like  manner  to,  the  rest  of  the  ventricular 
cavities  of  the  brain. 

The  Fornix.  Figs.  29,  31,  32,  35,  38,  39,  40,  43  to  47 
inclusive. 

The  fornix  is  a  double  band  of  fibres,  one  on  each  side 
of  the  median  line,  separated  in  front  and  behind  but  coming 
together  in  the  middle,  where  they  fuse  for  a  short  distance 
and  form  the  body.  The  anterior  and  posterior  separated 
portions  are  called  the  anterior  and  posterior  pillars  re- 
spectively. 

The  fornix  begins  at  the  base  of  the  brain,  as  the  anteinor 
pillars,  in  the  corpora  albicantia.  The  pillars  ascend  nearly 
vertically  and  at  the  anterior  extremity  of  the  third  ventricle 
until  they  nearly  reach  the  under  surface  of  the  corpus 
callosum,  then  they  turn  suddenly  backward  (the  genua) 
(leaving  an  aperture  extending  into  the  third  ventricle, 
which  is  the  foramen  of  Monro),  become  united  to  each 
other,  forming  the  body  of  the  fornix,  and  to  the  under 
surface  of  the  corpus  callosum.  After  a  short  distance 
they  again  diverge,  and,  as  the  posterior  pillars,  pass  outward 
and  downward  to  the  outer  surface  of  the  hippocampus 
major,  with  which  they  become  blended. 


218  A  MANUAL   OF  ANATOMY. 

The  anterior  pillars  and  the  anterior  part  of  the  body  of 
the  fornix  have  the  septum  lucidum  attached  to  them. 

The  posterior  pillar  of  the  fornix  is  flattened  and  its 
outer  margin  becomes  much  thinned,  especially  as  the 
hippocampus  major  is  neared ;  this  thin,  lateral,  external 
margin  of  the  posterior  pillar  of  the  fornix  is  called  the 
fimbria  (fringe). 

As  already  stated,  the  fornix  is  developed  from  the  inner 
portion  of  the  lamina  terminalis.     Page  173. 

The  under  surface  of  the  corpus  callosum  is  left  exposed 
(after  proper  dissection)  between  the  diverging  posterior 
pillars  of  the  fornix,  and  being  striated  is  called  the  lyre. 

The  Foramina  of  Monro.      Figs.  31,  32,  33,  38,  39,  43. 

Are  two  openings,  one  from  each  lateral  ventricle,  into 
the  cavity  of  the  third  ventricle.  They  establish  a  free 
communication  between  the  lateral  and  the  third  ventricles 
and  between  the  lateral  ventricles  themselves  (by  way  of 
the  third).  The  opening  is  semilunar  in  shape,  with  the 
concavity  pointing  downward  and  backward,  and  it  is  a  gap 
left  between  the  bend  or  genu  of  the  fornix  and  the  anterior 
extremity  of  the  optic  thalamus. 

Through  the  opening  of  Monro  pass  the  choroid  plex- 
uses into  the  third  ventricle. 


DISSECTION. 
Divide  the  body  of  the  fornix  and  reflect  the  two  portions.      Save  the 
velum  interpositum  and  its  choroid  plexuses. 

The  Velum    Interpositum    and     the    Choroid  Plexuses 
of  the  Cerebral  Ventricles.    Figs.  32,  33,  35,  36,  39. 
After  the  fornix  has  been  removed  the  vascular  mem- 
brane, which  is  called  the  velum  interpositum,  is  exposed. 
It  is  seen  to  have  a  triangular  shape  and  to  be  continuous 


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220  A  MANUAL  OF  A  ANATOMY. 

posteriorly  with  the  pia,  from  which  it  originally  springs. 
The  velum  interpositum  forms  the  covering  or  roof  for  the 
third  ventricle.  Its  margins  project  into  the  cavity  of  the 
lateral  ventricles  and  are  composed  of  masses  of  capillaries 
called  the  choroid  plexuses  of  these  ventricles. 

In  a  similar  manner  from  the  under  surface  of  the  velum 
festoons  of  capillaries  hang  downward  into  the  cavity  of 
the  third  ventricle  and  furnish  the  choroid  plexuses  for  that 
ventricle. 

As  stated  above,  the  velum  is  a  portion  of  the  pia  which 
seems  to  be  contained  within  the  ventricular  cavity  of  the 
brain.  But  such  is  not  really  the  case,  for  though  it 
projects  into  the  ventricles  of  the  brain  it  carries  in  front 
of  it  a  covering  of  epithelium  which  is  the  attenuated 
remains  of  the  roof  of  the  primitive  vesicles  of  the  brain. 
This  layer  covers  the  velum  and  the  choroid  plexuses  and 
becomes  continuous  with  the  walls  forming  the  boundaries 
of  the  ventricles  and  so  shuts  the  velum  and  choroid 
plexuses  out  of  the  cerebral  ventricles.      Diag.  15. 

The  velum  interpositum  with  its  lining  layer  of  epithe- 
lial cells  (which  represents  the  primitive  roof  of  the  brain) 
is  called  the  tela  choroidea  superior,  and  the  portion  of 
the  pia  which  reaches  from  the  under  surface  of  the  cere- 
bellum to  the  upper  surface  of  the  medulla,  and  forms  the 
covering  for  the  posterior  portion  of  the  fourth  ventricle, 
is  called  the  tela  choroidea  inferior. 

The  Deep  Cerebral  Veins. 

{a)  The  vein  of  the  corpus  striatum  collects  the  blood 
from  the  corpus  striatum,  optic  thalamus,  fornix,  septum 
lucidum,  courses  forward  and  inward  in  the  groove  between 
the  corpus  striatum  and  the  optic  thalamus,  and  terminates 
at  the  entrance  of  the  foramen  of  Monro. 


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222  A  MANUAL   OF  ANA  TOMY. 

{p)  The  choroid  vein  collects  the  blood  from  the  struc- 
tures of  the  descending  horn  of  the  lateral  ventricle, 
follows  along  the  margin  of  the  choroid  plexus  to  the 
foramen  of  Monro,  where  it  joins  the  vein  above  to  form 
the  vein  of  Galen. 

(r)  The  vein  of  Galen  is  formed  by  the  union  of  the 
veins  of  the  corpus  striatum  and  the  choroid  plexus  at  the 
foramen  of  Monro.  It  passes  backward  in  the  velum  inter- 
positum,  close  to  the  middle  Hne,  and  at  the  posterior 
margin  of  the  splenium  unites  with  a  corresponding  vein 
of  the  other  side  to  form  the  common  vein  of  Galen, 
which  is  about  half  an  inch  long  and  terminates  in  the 
straight  sinus.  Besides  the  veins  which  unite  to  form  it, 
the  vein  of  Galen  drains  the  third  ventricle,  and  the 
posterior  horn  of  the  lateral  ventricle,  and  the  common 
or  great  vein  of  Galen  the  superior  surface  of  the  cere- 
bellum. 

DISSECTION. 
Remove  the  velum  interpositum  and  the  choroid  plexuses,  being  careful 
in  doing  so  to  leave  the  pineal  gland  behind,  as  the  gland  is  firmly  adherent 
to  the  under  surface  of  the  posterior  part  of  the  velum. 

The  Third  Ventricle.     Figs.  33,  34,  39,  43  to  46,  50,  51, 

54- 

The  third  ventricle  is  now  exposed.  Its  boundaries  will 
be  seen  to  consist  of  the  following  parts  : — 

Laterally,  the  optic  thalami  and  the  crura  of  the  pineal 
gland ;  in  front,  by  the  anterior  pillars  of  the  fornix,  the 
anterior  commissure,  and  the  septum  lucidum  which  fills  in 
the  gap  between  the  pillars  of  the  fornix  ;  behind,  by  the 
posterior  commissure,  the  pineal  gland  and  its  diverging 
crura  ;  the  floor  is  composed  of  the  following  structures 
already  described  in  connection  with  the  base  of  the  brain, — 
(see  Fig.  29)  the  lamina  cinerea,  optic  chiasm,  tuber  cine- 


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224  A  MANUAL   OF  ANATOMY. 

reum,  infundibulum  (and  pituitary  gland),  the  corpora  albi- 
cantia,  and  tlie  posterior  perforated  space.  The  third  ven- 
tricle communicates  by  means  of  the  foramina  of  Monro 
with  the  lateral  ventricles  anteriorly,  and  through  the 
aqueduct  of  Sylvius  with  the  fourth  ventricle  posteriorly. 
The  opening  into  the  infundibulum  is  only  a  blind  one. 

The  Pineal  Gland.     Figs.  33,  39,  46,  47,  54. 

This  is  a  small  gland  located  between  the  posterior  ex- 
tremities of  the  optic  thalami  and  resting  upon  the  groove 
between  the  anterior  pair  of  the  quadrigeminal  bodies.  It 
is  about  as  large  as  a  small  pea,  and  is  connected  to  the 
rest  of  the  brain  by  a  divided  stalk,  the  lower  fibres  of 
which  connect  it  with  the  posterior  commissure,  the  upper 
fibres,  under  the  name  of  the  peduncles  of  the  pineal  gland, 
running  forward  along  the  optic  thalami,  marking  the 
junction  of  the  superior  and  internal  surfaces,  to  cross  the 
depression  at  the  floor  of  the  foramen  of  Monro  and  join 
the  anterior  pillars  of  the  fornix. 

The  Corpora  Quadrigemina.      Figs.    33,    38,  39,  40,  47, 

48,  53,  54- 

These  consist  of  four  rounded  elevations  arranged  in 
pairs,  situated  on  either  side  of  the  middle  line,  between 
the  optic  thalami  and  the  cerebellum,  and  upon  the  quad- 
rigeminal lamina  which  forms  the  roof  of  the  aqueduct  of 
Sylvius.  These  pairs  are  separated  from  each  other  by 
vertical  and  horizontal  intersecting  grooves,  forming  a 
crucial  sulcus.  The  anterior  or  superior  pair  of  elevations 
is  called  the  nates,  the  posterior  pair  the  testes. 

The  quadrigeminal  bodies  have  a  narrowing  prolongation 
forward  which  is  called  their  brachia,  or  arms.  Between 
these  brachia  and  close  to  the  groove  under  the  pulvinar  of 
the  optic  thalamus  is  the  internal  geniculate  body,  which 


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226  A  MANUAL  OF  ANATOMY. 

is  a  small   oval  nucleus  with  its   long  axis  placed  trans- 
versely.    Figs.  53,  54. 

The  external  geniculate  body  is  described  as  an  en- 
largement at  the  outer  portion  of  the  pulvinar,  with  which 
it  is  continuous.     See  Optic  thalami,  page  230. 

DISSECTION. 

One  half  of  the  cerebrum  should  now  be  carefully  sectioned  horizontally, 
and  the  other  half  transverse-vertically  as  far  as  the  beginning  of  the  aqueduct 
of  Sylvius.  From  these  sections  study  the  situation,  shape,  and  relations  of 
the  basal  ganglia  and  nerve  pathways. 

The  Corpora  Striata.  (Study  carefully  all  the  various 
sections,  especially  Figs.  30,  33,  35,  37,  43,  44,  51.) 

These  are  symmetrical  ovoid  elevations  of  gray  matter, 
which  project  into  the  floor  of  the  lateral  ventricles. 

A  corpus  striatum,  by  consulting  the  various  sections, 
will  be  seen  to  consist  of  an  oval  form  with  a  long  axis 
placed  anteroposteriorly.  It  is  located  internal  to  and 
opposite  the  central  lobe  of  the  cerebrum.  It  reaches  to 
and  forms  the  base  of  the  brain  corresponding  to  the 
anterior  perforated  space,  and  extends  into  the  cavity  of  the 
lateral  ventricle  as  the  caudate  nucleus.  It  will  be  seen  to 
consist  of  two  masses  of  gray  matter  separated  from  each 
other  by  a  sheet  of  white  fibres,  except  at  their  extreme 
anterior  inferior  portion. 

The  two  gray  masses  are  the  caudate  and  lenticular 
nuclei,  the  white  fibres  which  separate  them  the  internal 
capsule. 

The  Caudate  Nucleus. — This  is  the  inner  and  superior 
(also  anterior  and  posterior)  band  of  gray  matter  which  lies 
within  the  lateral  ventricle,  and  hence  is  the  intraventricu- 
lar portion  of  the  corpus  striatum.  It  is  wider  in  front, 
where  it  forms  a  prominent  elevation  in  the  anterior  horn, 


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228  A  MANUAL   OF  ANA  TOMY. 

but  narrows  as  it  extends  posteriorly,  forming  the  outer  por- 
tion of  the  floor  of  the  body  of  the  ventricle  ;  then  it  turns 
downward  into  the  descending  horn,  forming  in  this  position 
the  outer  portion  of  its  roof;  finally  it  terminates  in  the 
amygdaloid  nucleus,  which  is  placed  in  the  anterior  part 
of  the  roof  of  the  descending  horn. 

The  large  anterior  portion  in  the  anterior  horn  is  the 
head  of  the  caudate  nucleus  ;  its  body  corresponds  to  the 
body  of  the  ventricle  itself,  while  the  tail  of  the  nucleus  is 
its  slender  prolongation  into  the  descending  horn. 

The  nucleus  thus  describes  almost  a  complete  circle  and 
shows  two  cut  surfaces  in  horizontal  or  vertical  transverse 
sections. 

The  Lenticular  Nucleus. — Is  the  lower  and  outer — 
extraventricular — portion  of  the  corpus  striatum.  In 
horizontal  section  it  is  biconvex  in  shape  and  faces  inward 
and  outward  ;  in  vertical-transverse  section  it  is  triangular 
or  wedge-shaped,  with  the  base  of  the  wedge  abutting  on 
the  central  lobe ;  in  vertical  anteroposterior  sections  its 
outline  is  oval  with  its  lower  part  reaching  to  the  base  of 
the  brain  (at  the  anterior  perforated  space). 

The  lenticular  nucleus  is  separated  from  the  caudate 
nucleus  by  a  sheet  of  white  fibres — the  internal  capsule — 
which  bounds  it  on  the  inside.  There  is  a  similar  sheet  of 
white  fibres  bounding  the  nucleus  upon  its  external  surface 
called  the  external  capsule.  The  two  nuclei  are  not  en- 
tirely separated  by  the  internal  capsule,  as  will  be  seen  on 
study  of  a  series  of  anteroposterior  sections,  but  they  be- 
come continuous  with  each  other  around  the  anterior 
margin  of  the  internal  capsule  ;  they  are  also  connected  by 
numerous  fibres  which  pass  through  the  anterior  limb  of 
the  internal  capsule. 

A  vertical  transverse  section  of  the  nucleus  in  fresh  speci- 


230  A  MANUAL  OF  ANATOMY. 

mens  (and  in  the  original  photographs)  shows  the  lenticu- 
lar nucleus  to  consist  of  three  portions  vertically  divided 
by  thin  striations  of  white  fibres  (the  external  and  internal 
medullary  laminae).  The  two  inner  portions  of  the  nucleus 
are  lighter  in  color  than  the  outer  portion  ;  the  former  con- 
stitute the  globus  pallidus,  the  latter  the  putamen. 

The  Optic  Thalami.     Figs.  30,  33,  39,  40,  46,  51,  53,  54. 

These  are  double  structures,  which  form  the  lateral 
walls  for  the  third  ventricle  and  lie  internal  and  posterior  to 
the  corpora  striata.  An  optic  thalamus  is  somewhat  oval 
in  shape  with  the  long  axis  directed  anteroposteriorly.  It 
is  slightly  contracted  in  front  and  below,  and  expanded 
behind  and  above.  The  narrower  anterior  extremity  is 
the  anterior  tubercle,  which  forms  the  posterior  boundary 
for  the  foramen  of  Monro  ;  the  prominent  posterior  part  is 
the  posterior  tubercle,  or  the  pulvinar.  The  pulvinar 
terminates  externally  in  a  slight  oval  elevation,  which  is  the 
external  geniculate  body. 

The  superior  surface  of  the  optic  thalamus  forms  a  part 
of  the  floor  of  the  lateral  ventricle,  and  furnishes  support 
for  the  posterior  pillar  of  the  fornix  and  the  choroid 
plexus.  The  course  of  the  latter  is  indicated  on  the  thala- 
mus by  a  shallow  groove,  sulcus  choroideus,  which  divides 
the  upper  surface  into  two  portions,  the  external  being 
within  the  lateral  ventricle  and  the  internal  covered  by  the 
velum  interpositum.  The  internal  surface  forms  a  nearly 
vertical  wall  and  limits  the  third  ventricle  laterally.  It  is 
divided  from  the  superior  surface  by  the  peduncle  of  the 
pineal  gland  which  runs  forward  from  the  gland  to  join  the 
anterior  pillars  of  the  fornix. 

At  the  posterior  internal  part  of  the  superior  surface  of 
the  thalamus,  in  the   angle  between  the  peduncle  of  the 


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232  A  MANUAL   OF  ANATOMY. 

pineal    gland    and  the    pulvinar,  is    a    shallow   depression 
termed  the  trigonum  habenulae. 

The  optic  thalami  are  joined  by  two  connecting  bundles 
of  fibres, — the  middle,  gray  or  soft  commissure,  which 
unites  them  at  the  middle  of  their  opposing  surfaces,  and 
the  posterior  commissure,  which  unites  these  surfaces  be- 
neath the  pineal  gland  and  over  the  beginning  of  the  aque- 
duct of  Sylvius. 

The  Development  of  the  Corpus  Striatum,  Optic  Thal- 
amus, and  Internal  Capsule. 

The  optic  thalamus  and  the  corpus  striatum  are  devel- 
oped from  the  floor  (the  former)  and  the  floor  and  side 
wall  (the  latter)  of  the  fore  and  interbrains  opposite  and 
posterior  to  the  narrowing  orifice  which  connects  the  cavity 
of  the  fore  and  interbrains  (/.  e.,  the  future  foramen  of 
Monro).  They  first  appear  as  separate  swellings  distinct 
from  each  other  and  from  the  wall  of  the  vesicle,  but  later 
the  corpus  striatum  becomes  fused  along  its  line  of  con- 
tact with  the  vesicular  wall  and  also  to  the  optic  thalamus 
along  their  opposing  surfaces.      See  page  173. 

At  this  early  stage  the  corpus  striatum  does  not  show 
the  nuclei  that  distinguish  it  in  the  adult.  They  (the  cau- 
date and  lenticular  nuclei)  are  developed  later  as  masses 
of  gray  cells  which  are  bunched  together  in  the  supero- 
internal  and  infero-external  regions  of  the  corpus  striatum. 
From  these  cells  and  from  the  cortical  wall  (with  which 
the  corpus  striatum  has  now  become  fused),  white  fibres 
develop  which  pass  downward  and  inward,  separating  the 
two  portions  (caudate  and  lenticular)  from  each  other 
(except  at  their  extreme  anterior  and  inferior  parts),  and 
also  separating  the  corpus  striatum  from  the  optic  thala- 
mus.    This  white  layer  of  fibres  is  the  internal  capsule. 


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234  A  MANUAL  OF  ANA  TOMY. 

As  the  optic  thalami  grow  upward  they  approach  each 
other  and  become  united  along  their  opposing  surfaces. 
This  central  bond  of  union  later  diminishes  in  extent,  but 
persists  as  the  middle  commissure. 

The  fibres  of  the  internal  capsule  turn  downward  and 
backward  under  the  optic  thalamus  ;  thus  the  latter  is  said 
to  rest  upon  the  former. 

The  Internal  Capsule.      Figs.  32,  35,  45. 

From  what  has  been  said  it  will  be  apparent  that  this 
part  of  the  cerebrum  is  a  mass  of  white  fibres  which  pass 
from  the  cortex  and  ganglia  to  the  base  of  the  brain,  where 
they  appear  as  two  rounded  bundles  of  fibres  under  the 
name  of  the  crura  cerebri.     Fig.  29. 

From  a  vertical-transverse  section  the  internal  capsule 
will  be  seen  to  pass  upward  and  outward  between  the  optic 
thalamus  on  the  inside  and  the  lenticular  nucleus  on  the 
outside,  then  between  the  caudate  and  lenticular  nuclei,  and 
then  to  radiate  to  the  cortex  of  the  brain.  This  radiation 
of  the  fibres  of  the  internal  capsule  is  called  the  corona 
radiata,  and  takes  place  to  all  parts  of  the  cortex.    Fig.  37. 

On  a  horizontal  section  the  internal  capsule  presents  two 
portions  or  limbs,  an  anterior  and  posterior,  united  together 
at  an  angle  of  about  113  degrees.  The  angle  is  the  knee, 
and  is  at  the  gap  between  the  caudate  nucleus  and  the  optic 
thalamus. 

The  anterior  limb  lies  between  the  caudate  and  lenticular 
nuclei,  the  posterior  between  the  optic  thalamus  and  the 
lenticular  nucleus.  As  previously  stated,  the  lenticular 
nucleus  has  a  narrow  sheet  of  white  fibres  covering  its  ex- 
ternal surface  ;  this  is  the  external  capsule. 

Again  external  to  the  external  capsule  is  a  plate  of  gray 
matter — ^the  claustrum — which  is  placed  vertically,  and  in 


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236  A  MANUAL   OF  ANATOMY. 

area  corresponds  to  the  base  of  the  central  lobe  of  the 
brain. 

The  claustrum  is  connected  to  the  corpus  striatum  (len- 
ticular nucleus)  at  its  inferior  margin,  where  the  external 
capsule  is  wanting,  also  to  the  amygdaloid  nucleus. 

The  amygdaloid,  nucleus  (Figs.  37,  46,  51)  is  an  oval, 
gray  mass  continuous  with  the  cortex  of  the  apex  of  the 
temporal  lobe.  It  produces  a  bulging  into  the  anterior  part 
of  the  descending  horn  of  the  lateral  ventricle.  It  is  con- 
tinuous with  the  claustrum,  is  immediately  under  the  len- 
ticular nucleus,  and  has  terminating  in  it  the  tail  of  the 
caudate  nucleus,  the  tsenia  semicircularis,  also  fibres  from 
the  external  root  of  the  olfactory  nerve  tract  and  from  the 
anterior  commissure. 

The  taenia  semicircularis  (one  on  each  side,  Figs.  30, 
46),  is  a  round  bundle  of  white  fibres  which  starts  from  the 
anterior  pillar  of  the  fornix,  passes  outward  and  backward 
along  the  inner  border  of  the  body  and  tail  of  the  caudate 
nucleus,  between  this  nucleus  and  the  optic  thalamus,  then 
on  into  the  descending  horn  of  the  ventricle,  forming  the 
inner  part  of  its  roof,  to  terminate  in  the  amygdaloid  nucleus 
with  the  tail  of  the  caudate  nucleus. 

The  anterior  commissure  can  not  be  shown  for  its  en- 
tire length  in  any  one  section,  as  it  takes  a  curved  course. 
The  dissection  in  Fig.  34  (see  also  Figs.  37,  39,  43,  50) 
shows  the  commissure.  It  is  a  round  bundle  of  white 
fibres  (about  an  eighth  of  an  inch  in  diameter)  which  crosses 
the  anterior  part  of  the  third  ventricle  in  front  of  the  ante- 
rior pillars  of  the  fornix,  between  which  it  can  be  seen  from 
the  third  ventricle  ;  its  course  is  then  downward  and  back- 
ward beneath  the  lenticular  nucleus  to  terminate  in  the  sub- 
stance of  the  temporal  lobe  at  the  anterior  part  of  the 
roof  of  the  descending  horn  of  the  lateral  ventricle,  and 


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238  A  MANUAL   OF  ANA  TOMY. 

probably  in  the  amygdaloid  nucleus  as  well.  Its  fibres  are 
connected  with  the  fibres  which  constitute  the  middle  root 
of  the  olfactory  tract.  The  anterior  commissure  is  devel- 
oped from  the  lamina  terminalis. 

The  basal  gray  commissure  is  that  portion  of  the  floor 
of  the  third  ventricle  which  is  formed  by  the  lamina  cine- 
rea,  tuber  cinereum,  and  posterior  perforated  space. 

The  bundle  of  Vicq  d'  Azyr  is  a  band  of  white  fibres 
which  passes  from  a  corpus  albicans  vertically  into  the  an- 
terior extremity  (anterior  tubercle)  of  the  optic  thalamus. 
It  was  formerly  described  as  a  continuation  of  the  anterior 
pillar  of  the  fornix,  which,  after  reaching  the  base  of  the 
brain,  suddenly  bent  upward  on  itself  (forming  the  corpus 
albicans)  and  passed  to  the  optic  thalamus.  The  optic 
thalami,  pineal  gland,  pituitary  body,  and  the  upper  arm  of 
the  optic  nerve  arise  from  the  walls  of  the  interbrain,  while 
its  central  cavity  remains  as  the  third  ventricle. 

DISSECTION. 
After  studying  the  crura  cerebri  externally,  transverse  sections  should  be 
made  of  them  as  far  back  as  the  posterior  quadrigeminal  bodies. 

The  Crura  Cerebri.  Figs.  29,  38,  39,  40,  45,  46,  50,  53, 
These  are  the  rounded  bundles  of  fibres  which  pass  down- 
ward from  the  under  surface  of  the  cerebrum.  They  are 
oval  in  cross  section  and  united  along  the  posterior  half  of 
their  opposing  surfaces,  while  the  anterior  portions  are 
separated,  and  in  the  interval  between  them  is  found  the 
posterior  perforated  space  and  the  third  nerves.  The  crura 
cerebri  are  continuous  posteriorly,  around  the  aqueduct  of 
Sylvius,  with  the  quadrigeminal  lamina. 

Portions  of  the  crura  cerebri  have  been  named  for  pur- 
poses of  distinction.  On  a  transverse  section  there  will  be 
seen  a  dark  or  black  semilunar-shaped  nucleus,  which  is 


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240  A  MANUAL   OF  ANATOMY. 

placed  nearly  transversely  across  the  crus  at  about  its  mid- 
dle ;  this  is  the  locus  niger  and  divides  the  crus  into  the 
crusta  (anterior)  and  teginentuin  (posterior). 

The  crusta  and  tegmentum  are  also  separated  from  each 
other  on  their  outer  surface  by  two  grooves  which  run 
parallel  with  each  other.  One  groove  is  on  the  inner 
surface  of  the  crus  and  is  called  the  oculomotor  groove, 
because  out  of  this  groove  the  third  or  oculomotor  nerve 
emerges  ;  the  other  groove  is  placed  externally  and  called 
the  lateral  groove  of  the  crus. 

The  crusta  is  composed  of  fibres  which  pass  through  the 
pons  and  appear  as  the  anterior  pyramids  of  the  medulla, 
and  of  connecting  fibres  to  the  opposite  cerebellar  hemi- 
sphere. These  fibres,  continued  upward,  pass  under  the  optic 
thalamus  and  take  part  in  forming  the  internal  capsule. 

The  tegmentum  is  composed  of  fibres  passing  from  the 
internal  capsule  to  the  medulla  and  cerebellum. 

The  red  nucleus  (Figs.  34,  40,  46,  51)  is  a  round 
nucleus  of  brow^nish-gray  matter,  with  a  diameter  of  about 
three-eighths  of  an  inch  ;  it  is  situated  in  the  tegmentum 
behind  the  middle  of  the  locus  niger  and  under  the  posterior 
part  of  the  optic  thalamus. 

External  to  the  red  nucleus,  on  the  same  plane  with  it, 
but  extending  backward  so  as  to  appear  behind  it,  is  a 
second  gray  nucleus,  the  subthalamic  g-anglion,  or  the 
body  of  Luys.  The  plane  of  junction  of  the  opposite 
tegmenta  is  called  the  median  raphe. 

The  Aqueduct  of  Sylvius.     Figs.  34,  39,  47. 

This  is  the  small  canal  which  connects  the  third  with  the 
fourth  ventricle.  It  passes  beneath  the  posterior  commis- 
sure and  the  lamina  quadrigemina,  and  lies  in  the  raphe 
between  the  tegmental  tracts. 


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242  A  MANUAL   OF  ANATOMY. 

The  crura  cerebri,  quadrigeminal  lamina  and  bodies,  and 
lower  arm  of  the  optic  tract  are  developed  from  the  primi- 
tive midbrain,  and  the  aqueduct  of  Sylvius  is  the  remains 
of  the  cavity  within  this  vesicle. 

The  Cerebellum.     Figs.  29,  34,  37  to  40,  52  to  56. 

This  consists  of  two  symmetrical  halves  united  at  their 
opposing  surfaces  along  a  posterior  median  plane,  and 
also,  like  the  cerebral  hemispheres,  by  a  wide  cross-band 
of  commissural  fibres  which  passes  anterior  to  the  back- 
ward prolongation  of  the  crura  cerebri,  and  is  called  the 
pons. 

The  Lobes  of  the  Cerebellum. — "  In  descriptive  an- 
atomy an  astounding  variety  of  names  are  applied  to  the 
various  parts  of  each  lobe  ;  it  would  be  an  essential  gain  if 
at  least  three-fourths  of  these  names  could  be  discarded." 
(Minot's  "  Embryology.")  The  cerebellum  is  divided  into 
five  primary  lobes  by  four  sulci. 

The  superior  surface  of  the  cerebellum  is  divided  into 
two  lobes,  the  quadrate  and  the  posterosuperior.  The 
former  is  subdivided  into  the  anterior  and  posterior  crescen- 
tic  portions. 

The  under  surface  of  the  cerebellum  presents  the  floccu- 
lus, a  small  but  prominent  rounded  lobe  close  to  the  pos- 
terior part  of  the  pons.  Behind  this  and  close  to  the 
medulla,  the  tonsillar  or  amygdaloid  lobe.  Behind  these 
are  the  cuneate,  slender,  and  postero-inferior  lobes. 

Between  the  under  surfaces  of  the  cerebellar  hemispheres 
is  a  deep  notch — the  vallecula — for  the  reception  of  the 
medulla. 

The  junction  of  the  cerebellar  lobes  along  the  median 
plane  is  marked  by  a  rounded  elevation  called  the  superior 
and  the  inferior  vermis.     These  are  further  subdivided  by 


Fig.  50.  Oblique -Transverse  Section  Through  the  Medulla,  Pons,  Crura, 
AND  Cerebrum.  Viewed  from  in  front. — a.  Great  longitudinal  fissure,  d,  Genu  of  cor- 
pus callosum.  c,  Fifth  ventricle,  d.  Anterior  horn,  lateral  ventricle,  e,  Caudate  nucleus. 
/,  Internal  capsule,  g-,  Lenticular  nucleus,  h,  h.  Anterior  commissure.  /,  Optic  tract. 
j.  Amygdaloid  nucleus,  k,  Hippocampus  major.  /,  Middle  horn  lateral  ventricle. 
m.  Fissure  of  Sylvius  and  island  of  Reil.  w,  w,  «,  Motor  tract  in  crusta,  pons,  and  me- 
dulla, o,  Corpora  albicantia.  p.  Pons,  q.  Medulla,  r.  Cerebellum  showing  arbor  vitae. 
s,  Anterior  pillar  of  forni.x.  x.  Third  ventricle.  ?<,  External  capsule,  z',  Claustrum,  be- 
coming continuous  with  lenticular  nucleus  at  lower  part. 


244  A  MANUAL  OF  ANATOMY. 

an  unnecessary  refinement  of  description  into  seven  other 
lobules. 

The  cerebellum  is  connected  to  the  rest  of  the  brain  by 
three  pairs  of  nerve-bundles,  or  peduncles  :  the  superior, 
middle,  and  inferior. 

The  middle  peduncles  have  already  been  referred  to  as 
the  great  transverse  commissure  or  the  pons,  which  unite 
the  two  hemispheres  of  the  cerebellum  in  front  of  the  fibres 
of  the  crura  cerebri. 

The  superior  peduncles  are  flattened  bundles  which 
project  backward  and  outward  from  the  testes  of  the  corpora 
quadrigemina  to  reach  the  cerebellum  internal  to,  and  in 
front  of,  the  middle  peduncles. 

The  superior  peduncles  are  united  across  the  median  line 
and  from  the  posterior  margin  of  the  quadrigeminal  lamina 
to  the  front  of  the  under  surface  of  the  cerebellum  by  a 
thin  sheet  of  white  matter  called  the  valve  of  Vieussens, 
or  the  superior  medullary  velum.  A  tongue-shaped  pro- 
jection— the  lingula — from  the  superior  vermiform  process 
of  the  cerebellum  rests  upon  the  posterior  part  of  the  velum. 

An  extension  of  some  fibres  from  the  valve  of  Vieussens 
forward  between  the  posterior  pair  of  quadrigeminal  bodies 
is  called  the  frenulum  veli. 

The  inferior  peduncles  of  the  cerebellum  connect  it  with 
the  lateral  regions  of  the  posterior  part  of  the  medulla. 
They  are  formed  of  the  fibres  from  the  direct  cerebellar 
tract,  the  internal  and  the  external  arciform  fibres,  and  go 
under  the  name  of  the  restiform  tracts.  They  enter  the 
cerebellum  internal  to  and  behind  the  middle  peduncles. 

On  sections  of  the  cerebellum  the  peculiar  arrangement 
of  its  white  matter  within  the  gray  gives  the  appearance  of 
a  branching  tree,  hence  the  name  of  arbor  vitse  which  is 
applied  to  it. 


Fig.  51.  Oblique-Transverse  Section  Through  Medulla,  Pons,  Crura,  and 
Cerebrum.  Viewed  from  in  front.— a,  Optic  thalamus.  *,  Third  ventricle,  c,  Red 
nucleus,  d,  Locus  niger.  ^,  <>,  Caudate  nucleus.  /,  Lenticular  nucleus.  ^,  Floor  of  the 
fourth  ventricle.     Remaining  parts  as  in  preceding  figure. 


246  A  MANUAL  OF  ANATOMY. 

Within  the  stalk  of  white  matter  are  situated  four  pairs 
of  gray  nuclei.  The  most  conspicuous  pair,  situated  within 
the  centre  of  the  white  matter,  is  an  oval  nucleus  with  a 
dentated  or  serrated  outline,  and  in  consequence  is  called 
the  corpus  dentatum. 

The  Pons.      Figs.  29,  38  to  40,  47  to  49,  53.     \ 

This  is  the  portion  of  brain  which  intervenes  between  the 
crura  and  the  medulla,  and  consists  of  anteroposterior 
fibres  crossed  transversely  by  the  fibres  connecting  the 
hemispheres  of  the  cerebellum  as  stated  above. 

The  pons  is  about  an  inch  wide  along  the  median  line 
and  narrows  to  half  that  width  as  it  enters  the  cerebellum. 
It  presents  a  shallow  depression,  in  the  middle  line  in  which 
the  basilar  artery  rests.     See  page  158. 

The  upper  and  lower  or  anterior  and  posterior  borders 
of  the  pons  are  well  marked.  At  the  upper  border  the 
crura  cerebri  pass  backward  out  of  sight,  and  at  the  lower 
border  their  continuation  appears  as  the  medulla. 

The  posterior  surface  of  the  pons  will  be  described  with 
the  fourth  ventricle,  of  which  it  forms  the  anterior  portion. 

On  section,  the  pons  presents  two  distinct  areas.  The 
ventral  or  anterior,  and  the  tegmental  or  posterior  (continu- 
ous with  the  tegmentum  of  the  crura  cerebri).  The  de- 
scription of  the  subdivisions  of  these  regions  belongs  to  the 
histology  of  the  brain. 

The  cerebellum  and  the  pons  are  developed  from  the 
hindbrain,  the  former  from  its  roof  and  the  latter  from  its 
floor,  while  the  cavity  of  the  hindbrain  remains  as  the  an- 
terior part  of  the  fourth  ventricle. 

The  Medulla.     Figs.  29,  53,  54. 

This  portion  of  the  brain  extends  from  the  pons  back- 
ward for  about  an  inch  and  a  quarter  to  the  margin  of  the 


Fig.  52.  Oblique-Transverse  Section  THRorcH  Cerebellum,  Corpora  Qua- 
DRiGEMiNA,  AND  CEREBRUM.  Viewed  from  in  front  { the  under  side).— a,  Optic  thalamus. 
b,  Posterior  commissure,  c.  Roof  of  the  aqueduct  of  Sylvius,  d.  Under  surface  of  the 
corpora  quadrigemina.  e,  Superior  peduncle  of  cerebellum.  /,  Under  surface  of  the 
valve  of  Vieussens  with  the  lingula.  g.  Fourth  ventricle.  A,  Corpus  dentatum  01 
cerebellum. 


248  •  A  MANUAL  OF  ANA  TOMY. 

foramen  magnum,  below  which  it  is  continued  as  the  spinal 
cord.  It  is  about  three-quarters  of  an  inch  wide  at  the 
pons  and  three-eighths  of  an  inch  at  its  terminus. 

The  Under  Surface  of  the  Medulla. — Through  the 
middle  of  the  medulla  from  before  backward  extends  a 
fissure — the  anterior  median  fissure — which  divides  it  into 
two  symmetrical  halves.  The  fissure  terminates  at  the  pos- 
terior margin  of  the  pons  in  a  slightly  enlarged  cavity 
named  the  foramen  caecum. 

About  an  inch  behind  the  pons  the  anterior  fissure  will 
be  found  crossed  by  fibres  passing  from  one  side  of  the 
medulla  to  the  other.  This  is  the  decussation  of  the  an- 
terior pyramids  of  the  medulla. 

Along  the  side  of  the  anterior  median  fissure  lie  two  well- 
marked  ridges  or  bundles,  which  are  the  anterior  pyramids 
of  the  medulla.  They  are  limited  externally  by  shallow 
grooves  termed  the  anterolateral  sulci;  and  external  to 
these  grooves  are  the  lateral  tracts  or  columns  of  the 
medulla. 

At  the  outer  side  of  the  anterior  pyramids  and  close  to 
the  pons  is  developed  a  small  oval  nucleus — ^the  olivary- 
body.  The  anterolateral  groove  is  continued  along  the 
front  of  the  olivary  body  and  an  offset  from  it  around  the 
back  part  called  the  posterior  olivary  sulcus. 

Just  at  the  olivary  body  the  anterolateral  groove  is  in- 
terrupted by  a  thin  lamella  of  fibres  which  curve  around 
from  the  anterior  to  the  posterior  parts  of  the  nucleus  and 
are  called  the  external  arciform  fibres. 


DISSECTION. 
Divide  the  cerebellum  along  its  median  plane,  open  the  halves,  and  expose 
the  fourth  ventricle. 


Fig.  53.  Side  View  of  Medulla,  Pons,  Crus  Cerebri,  with  the  Sectioned 
Cerebellum  and  Cerebrcm. — ",  Lenticular  nucleus,  b,  Pulvinar  of  optic  thalamus. 
c.  External  geniculate  body,  d.  Optic  tract,  e,  Optic  nerve.  /,  Internal  geniculate 
body.  ^,  Nates,  k,  Testes,  of  corpora  quadrigetnina.  i.  Fillet.  /,  Superior  cerebellar 
peduncle,  k,  Crusta.  /,  External  lateral  groove,  m,  Pons,  w,  Fifth  nerve,  o,  Sixth 
nerve,  p,  Seventh  nerve,  q.  Eighth  nerve,  r.  Ninth  and  tenth  nerves,  s,  Eleventh 
nerve.  /,  Twelfth  nerve,  w.  Olivary  body,  v,  Medulla,  'c.  Middle  peduncle  of  cere- 
bellum.   X,  Cerebellum,    y,  Anterior  perforated  space  with  entering  vessels. 


250  A  MANUAL  OF  ANATOMY. 

The  Fourth  Ventricle  and  the  Posterior  and  Lateral 
Tracts  of  the  Medulla.      Figs,  39,  54. 

The  fourth  ventricle  is  an  elongated,  diamond-shaped 
space  communicating  anteriorly  by  means  of  the  aqueduct 
of  Sylvius  with  the  third  ventricle  and  posteriorly  with  the 
minute  central  canal  of  the  spinal  cord.  The  lateral  angles 
of  the  space  are  in  the  recesses  left  by  the  junction  of  the 
peduncles  at  the  side  of  the  cerebellum. 

The  roof  of  the  ventricle  is  formed  from  before  back- 
ward by  the  valve  of  Vieussens,  the  under  surface  of  the 
cerebellum,  and  the  portion  of  pia  which  forms  the  choroid 
plexus  of  the  fourth  ventricle  and  extends  from  the  postero- 
inferior  surface  of  the  cerebellum  to  the  upper  surface  of 
the  lower  part  of  the  medulla.  Remember  that  this  por- 
tion of  pia  is  composed  of  loops  of  capillaries,  over  which 
is  laid  the  layer  of  cells  which  represents  the  attenuated 
roof  of  the  posterior  afterbrain,  and  consequently  the 
plexus  is  shut  out  from  the  ventricular  cavity.  This  layer 
of  pia  with  its  choroid  plexus  and  lining  membrane  of  epi- 
thehum  is  called  the  tela  choroidea  inferior.  Also,  re- 
member that  the  tela  inferior  is  perforated  in  the  middle 
line  and  near  the  medulla  by  the  foramen  of  Magendie,  and 
in  the  lateral  recesses  by  narrow  slits  of  the  foramina  of 
Key  and  Retzius.  Through  these  apertures  a  free  com- 
munication is  offered  to  the  cerebrospinal  fluid  to  pass  from 
the  subarachnoidean  spaces  into  the  cavity  of  the  ventricles 
of  the  brain. 

The  Lateral  Boundaries  of  the  Fourth  Ventricle. — 
These  are  :  In  front,  the  superior  peduncles  ;  in  the  middle, 
the  junction  of  the  superior,  middle,  and  inferior  peduncles 
with  each  other  and  with  the  cerebellum  ;  the  posterior 
portion,  by  the  inferior  peduncles  (restiform  tracts),  the 
fasciculi  graciles,  and  their  clavae. 


Fig.  54.  Superior  Surface  of  Medulla  (cerebellum  removed),  Corpora  Quadri- 
GEMiNA,  AND  OPTic  Thalami  (cerebrum  removed).— a,  Optic  thalamus,  b,  Pulvinar. 
c  External  geniculate  body,  d.  Internal  geniculate  bodv.  e.  External  lateral  groove. 
/,  Third  ventricle,  g.  Peduncle  of  pineal  gland,  k,  Nates  i.  Testes.  Between  them 
the  crucial  ridge,  j.  Frenulum  veli,  and  the  sectioned  valve  of  Vieussen,';.  k,  Superior 
cerebellar  peduncle.  /,  Middle  cerebellar  peduncle,  w,  Inferior  cerebellar  peduncle. 
«,  Striae  acusticae.  o.  Posterior  median  fissure,  leading  anteriorlv  under  the  corpora 
quadrigemina  into  the  aqueduct  of  Sylvius,  and  posteriorly  by  {  /  )  the  calamus  srriptorius, 
mto  the  central  canal  of  the  spinal  cord,  p,  Fovea  anterior  or  supTior.  n.  Fasciculus 
teres,  r,  Fovea  posterior  or  inferior.  5,  Calamus  scriptorius.  /,  Poslei  inr  medi'ii  fis- 
sure of  cord  u,  Clava.  v.  Funiculus  gracilis,  w.  Funiculus  cuneatus.  x,  Sulcus 
posterolateral,    y,  Restiform  body. 


252  A  MANUAL   OF  ANA  TOMY. 

The  floor  of  the  fourth  ventricle  is  the  widely  separ- 
ated internal  surface  of  the  pons  and  medulla.  It  is  tra- 
versed along  the  median  line  by  a  fissure — the  posterior 
median  sulcus. 

Parallel  with  the  anterior  half,  and  on  either  side  of  the 
posterior  median  sulcus,  is  a  rounded  ridge — the  fasciculus 
teres — which  is  produced  by  the  fibres  of  the  facial  nerve. 

A  small  depression  is  in  the  lateral  recess  opposite  the 
posterior  part  of  the  eminentia  teres,  the  fovea  superior, 
and  in  front  of  this  depression  is  a  small  bluish  spot,  the 
locus  cseruleus. 

Some  transverse  fibres  are  seen  crossing  the  floor  of  the 
ventricle  just  behind  the  lateral  recesses  ;  these  are  a  part 
of  the  auditory  nerve  and  are  named  the  striae  acusticse. 
They  cross  a  little  elevation,  which  is  the  tuberculum  acus- 
ticum.  Behind  this  tubercle  is  a  second  shallow  depres- 
sion, which  is  the  fovea  inferior.  Extending  backward 
and  inward  from  the  inferior  fovea  is  the  ala  cinerea,  a 
dark  area  over  the  nuclei  of  the  ninth  and  tenth  nerves. 

The  ventricle  narrows  to  a  pointed  extremity — the  cala- 
mus scriptorius — which  is  contained  within  the  clavae  of 
the  funiculi  graciles. 

Internal  to  the  ala  cinerea  is  another  small  elevation,  the 
trigonum  hypoglossi,  which  is  over  the  nucleus  for  that 
nerve. 

The  Posterior  and  Lateral  Surfaces  of  the  Medulla. — 
Back  of  the  fourth  ventricle  the  sides  of  the  medulla  come 
together,  the  space  between  them  being  called  the  poste- 
rior median  fissure. 

By  the  anterior  and  posterior  median  fissures  the  medulla 
is  divided  into  two  lateral  halves  ;  each  half  of  the  medulla 
is  further    subdivided  by  the    antero-    and   posterolateral 


F'S-  55-  The  Under  Surface  of  the  Cerebellum  Viewed  from  Behind.— 
a,  Middle,  b,  Superior,  c,  Inferior  cerebellar  peduncles,  d,  Roof  of  fourth  ventricle. 
e,  Central  lobe.  The  lingula  removed  with  the  valve  of  Vieussens.  y,  ^,  h.  Inferior 
vermiform  process,  called,  respectively,  the  nodule,  uvula,  and  the  pyramid,  i,  Floc- 
culus. J,  Amygdala,  or  tonsil.  ^,  Cuneate  lobe.  /,  Slender  lobe,  m,  »t,  Postero- 
inferior  lobe.    «,  Beginning  of  the  great  horizontal  fissure  of  the  cerebellum,     o,  Incisura. 


F'K-  56.  Superior  Surface  of  the  Cerebellum  Viewed  from  Behind. — 
a.  Anterior  crescent,  d,  Posterior  crescent,  the  two  constituting  the  quadrate  lobe,  c  and 
d  form  the  posterosuperior  lobe.  i,  The  superior  cerebellar  sulcus.  2,  The  great 
horizontal  fissure  of  the  cerebellum,  e,  f,  and  g,  The  superior  vermiform  process. 
A,  Postero-inferior  lohe. 


254  A  MANUAL   OF  ANATOMY. 

fissures,  or  sulci,  into  three  areas — anterior,  lateral,  and 
posterior. 

The  anterior  area  is  occupied,  as  already  given,  by  the 
anterior  pyramids,  the  lateral  area  by  the  lateral  tract  below 
and  the  olivary  bodies  above.  The  posterior  tract  is  sub- 
divided by  a  shallow  fissure  into  two  tracts  :  An  internal 
one,  the  funiculus  gracilis,  and  an  external  one,  the  funicu- 
lus cuneatus. 

The  funiculus  gracilis  borders  upon  the  posterior 
median  fissure,  and  as  this  opens  to  form  the  fourth  ventri- 
cle, the  funiculus  forms  its  posterior  lateral  boundary. 

At  the  beginning  of  the  ventricle  the  funiculus  is  enlarged 
to  form  the  clava. 

The  funiculus  gracilis  terminates,  before  the  cerebellum 
is  reached,  in  a  fine  point. 

The  funiculus  cuneatus  runs  parallel  with  the  funiculus 
gracilis  and  external  to  it.  It  terminates  just  beyond  the 
lower  part  of  the  fourth  ventricle. 

What  appears  to  be  the  direct  continuation  of  the  funi- 
culus cuneatus  and  the  lateral  tract  passes  up  to  the  cere- 
bellum under  the  name  of  the  restiform  tract.  But  this 
tract  is  composed  of  fibres  derived  from  the  direct  cere- 
bellar tract,  and  the  internal  and  external  arciform  tracts. 

The  external  arciform  tract  is  a  thin  lamina  of  fibres 
which  issue  from  the  anterior  median  fissure  and  pass  out- 
ward across  the  pyramids,  below  the  olivary  body,  to  the 
restiform  tract. 

The  medulla  is  developed  from  the  afterbrain,  and  the 
posterior  part  of  the  fourth  ventricle  from  the  cavity  of  the 
same. 


UPPER  EXTREMITY  AND   THORAX,  ANTERIOR.       255 


THE  UPPER  EXTREMITY  AND  THORAX, 
Anterior. 

The  Landmarks. 

In  the  median  line  there  is  the  suprasternal  or  interclavi- 
cular notch  between  the  large  rounded  ends  of  the  clavicles. 
This  notch  is  always  easily  felt  even  in  very  fleshy  people, 
and  is  therefore  a  very  valuable  reference  point.  The  notch 
is  directly  in  front  of  the  disk  between  the  second  and  third 
dorsal  vertebrae,  and  two  and  one-half  inches  from  it. 
About  two  inches  below  the  notch  is  a  prominent  transverse 
ridge  marking  the  articulation  of  the  first  and  second  por- 
tions of  the  sternum.  This  ridge  is  also  a  guide  to  the 
second  ribs  and  cartilages  which  join  the  sternum  at  this 
place.  At  the  lower  end  of  the  sternum  is  the  ensiform 
appendix,  which  can  be  felt  on  pressure,  also  the  transverse 
ledge  or  jog  which  marks  where  the  appendix  unites  with 
the  second  piece  of  the  sternum.  This  place  receives  the 
cartilages  of  the  seventh  ribs,  and  is  therefore  a  guide  to 
them.  The  tip  of  the  ensiform  is  in  front  of  the  body  of 
the  ninth  dorsal  vertebra. 

For  the  remarks  concerning  the  lower  margin  of  the 
thorax,  see  page  432.  The  nipples  are  usually  given  as 
points  from  which  to  reckon  distances  and  relations.  Their 
position  is  so  variable,  especially  in  the  female,  as  to  scarcely 
deserve  mention  ;  however,  it  will  be  given  here.  As  a 
rule,  in  both  sexes  they  are  found  over  the  fourth  interspace, 
in  males  about  three  and  one-half  inches,  and  in  females 
four  inches,  from  the  median  line,  or  about  one  inch  ex- 
ternal to  the  junction  of  the  ribs  and  cartilages. 

The  clavicles  are  distinct,  and  extend  outward  and  slightly 
upward  from  the  lateral  margin  or  angle  of  the  manubrium 


256  A  MANUAL   OF  ANATOMY. 

to  join  the  acromion  process  of  the  scapula,  and  thus  hinge 
the  upper  extremity  to  the  thorax. 

The  articulation  between  the  clavicle  and  the  acromion  is 
usually  easily  found,  and  often  is  so  prominent  as  to  consti- 
tute almost  a  subluxation  of  the  former  upon  the  latter. 
The  margin  of  the  acromion  can  be  traced,  and  the  angle 
formed  by  the  junction  of  the  spine  with  the  acromion  is 
always  easily  located.  This  point  is  the  one  from  which 
measurements  are  made  in  determining  differences  in  the 
length  of  the  upper  extremity.  The  lower  fixed  points 
depend  upon  the  part  to  be  measured.  If  only  the  arm, 
the  external  condyle  of  the  humerus  or  the  tip  of  the  olec- 
ranon with  the  forearm  flexed  to  a  right  angle.  For  the 
arm  and  forearm,  the  tape  is  carried  to  the  tip  of  the  styloid 
process  of  the  radius  or  ulna,  and  for  the  entire  extremity, 
to  the  point  of  the  middle  finger  (any  finger  or  point  will 
do  provided  the  corresponding  point  is  taken  on  the  opposite 
side  of  the  body). 

In  front  of  the  middle  and  outer  thirds  of  the  clavicle  is 
usually  a  depression  corresponding  to  the  interval  between 
the  pectorahs  major  and  deltoid  muscles  ;  in  this  depression 
the  tip  of  the  coracoid  process  will  be  found  by  making  a 
little  pressure. 

The  cephalic  vein  lies  in  the  groove  between  the  deltoid 
and  pectoralis  major  muscles  and  passes  upward  to  empty 
into  the  axillary  vein  below  the  middle  of  the  clavicle. 

The  deltoid  tubercle  may  be  prominent  enough  to  be  dis- 
cerned by  touch  at  the  outer  and  middle  thirds  of  the  anterior 
border  of  the  bone.  Under  the  deltoid  muscle  the  tuber- 
osities of  the  humerus  can  be  felt,  especially  on  rotation 
of  the  bone.  The  greater  is  external,  the  lesser  internal, 
and  between  them  is  the  bicipital  groove,  which  can  be 
appreciated  in  thin  people. 


UPPER  EXTREMITY  AND   THORAX,  ANTERIOR.       257 

By  raising  the  arm  half  way  to  a  right  angle  from  the 
body,  the  anterior  and  posterior  boundaries  of  the  axillary 
space  will  appear,  the  pectoralis  major  in  front  and  the 
latissimus  dorsi  behind.  Between  them  is  the  cavity  of  the 
axilla.  By  carrying  the  fingers  high  up  in  this  cavity  the 
head  of  the  humerus  can  be  felt. 

The  line  of  the  axillary  artery  :  Extend  the  arm  until  it 
is  at  rig-ht  angles  with  the  trunk,  then  draw  a  line  from  the 
middle  of  the  clavicle  to  the  depression  at  the  inner  border 
of  the  coracobrachialis  and  biceps  muscles. 

The  pectoral  border  leads  down  to  the  fifth  rib. 

To  count  the  ribs,  remember  that  the  second  rib  joins 
the  sternum  (through  its  cartilage)  at  the  articulation  be- 
tween the  first  and  second  pieces  of  the  sternum  ;  that  the 
seventh  at  the  junction  of  the  second  and  third  parts  of  the 
sternum  ;  that  the  fourth  rib  is  just  above,  and  the  fifth 
just  below  the  nipple;  that  the  tenth,  eleventh,  and 
twelfth  can  be  located  by  touch  along  the  lower  border 
of  the  thorax. 

The  arm  presents  a  prominence  in  front  due  to  the  bi- 
ceps muscle,  and  a  slight  depression  at  its  outer  and  inner 
margins  ;  in  the  outer  lies  the  cephalic  vein  and  in  the  inner 
the  brachial  artery,  and  veins  with  the  median  nerve.  The 
inner  margin  of  the  muscle  is  the  guide  to  the  artery.  A 
similar  prominence  is  upon  the  back  of  the  arm,  formed  by 
the  triceps  muscle. 

At  the  elbow  recognize  the  two  (epi)  condyles  of  the 
humerus,  the  olecranon  process  of  the  ulna,  and  the  head 
and  tuberosity  of  the  radius.  The  internal  (epi)  condyle, 
being  more  prominent  than  the  external,  is  more  often 
broken  off  than  the  external.  It  points  in  the  direction  to 
w^iich  the  head  of  the  humerus  faces. 

The  prominent  olecranon  behind  bears  certain  relations 
17 


258'  A  MANUAL   OF  ANATOMY. 

to  the  condyles   of  the  humerus  in  the  normal  state  that 
must  be  kept  in  mind  : — 

(i)  When  the  forearm  is  extended  on  the  arm,  the  top 
of  the  olecranon  and  the  two  condyles  are  all  in  the  same 
straight  line. 

(2)  If  the  forearm  is  flexed  to  a  right  angle  with  the 
arm,  the  condyles  and  the  tip  of  the  olecranon  are  in  the 
same  plane.  The  coronoid  process  of  the  ulna  may  be 
found  in  front  of  the  inner  part  of  the  elbow  on  deep  pres- 
sure. It  is  usually  not  easily  distinguished.  The  head 
of  the  radius  will  be  felt,  on  rotation  of  the  shaft,  three- 
fourths  of  an  inch  below  the  external  condyle.  The 
"carrying  angle  :  "  This  is  the  normal  angle  (10°)  formed 
by  the  arm  and  the  supinated  forearm  ;  its  opening  is  out- 
ward. It  is  produced  by  the  trochlear  surface  of  the 
humerus  being  prolonged  lower  on  the  inside  than  outside 
and  thus  throwing  the  lower  end  of  the  ulna  outward. 
The  angle  may  be  lost  in  fractures  involving  the  condyles 
of  the  humerus  and  should  always  be  restored  ;  if  not 
maintained,  a  peculiar  deformity — gun-stock — remains. 

The  shafts  of  the  ulna  and  radius  terminate  below  in 
their  respective  styloid  processes.  Demonstrate  that  the 
styloid  process  of  the  radius  is  about  one-fourth  of  an  inch 
lower  than  that  of  the  ulna.  If  this  relation  is  altered  so 
as  to  bring  the  processes  in  the  same  line  it  shows  that  a 
fracture  of  one  or  the  other  bones  has  occurred.  In  the 
reduction  of  the  usual  (Colles's)  fracture  of  the  wrist  see 
that  the  normal  relation  is  reproduced. 
Outlining'  the  Heart  and  Lungs.      Figs.  57,  58,  59. 

The  student  now  should  take  time  to  mark  out  the  super- 
ficial outlines  of  the  heart,  lungs,  and  great  vessels  upon 
the  exterior  of  the  chest.  The  relations  of  the  heart  given 
below  are  the  results  of  the  writer's  own  investigations  in 


F'g-  57'  Composite  Chest-Heart  Photograph.  [From  a  paper  by  the  author  on 
"  The  Relations  of  the  Heart  and  Lungs  to  the  Anterior  Chest-Wall,  as  Determined  by 
Composite  Photography."  Abstract  read  before  the  Sections  in  Anatomy  and  General 
Surgery  of  the  First  Pan-American  Medical  Congress  at  Washington,  September  9,  1893, 
and  published  in  the  Neiu  York  Medical Joiirtial,  November  11  and  December  9,  1893.] — 
a.  Right  auricle,  b,  Left  auricle,  c.  Ventricles  of  heart,  in  a  moderately  expanded  con- 
dition, d,  Anterior  branch  of  right  coronary  artery.  Right  marginal,  e.  Left  coronary 
artery,  f,  Pulmonary  artery.  §-,  Aorta.  A,  Superior  vena  cava,  z.  Manubrium,  y,  Sterno- 
mastoid.    k,  k,  Nipples. 


260  A  MANUAL   OF  ANATOMY. 

1893  with  the  camera  (see  "Relations  of  the  Heart  and 
Lungs  to  the  Anterior  Chest  Wall,"  as  determined  by 
composite  photographs,  published  in  the  Medical  Journal 
of  November  11  and  December  9,  1893)  and  by  compari- 
son of  the  conflicting  statements  of  the  various  authors. 

(i)  Base  of  Heart. — A  line  crossing  the  sternum  ob- 
liquely from  the  upper  margin  of  the  third  right  to  the 
lower  border  of  the  second  left  costal  cartilage,  an  inch 
and  a  half  from  the  median  line  on  each  side. 

(2)  Apex. — In  the  fifth  space  near  the  upper  margin  of 
the  sixth  costal  cartilage,  two  and  a  half  inches  to  the  left 
of  the  median  line. 

(3)  Right  Border. — From  the  right  end  of  the  base 
curved  slightly  outward  to  reach  a  point  an  inch  and  three- 
quarters  from  the  right  of  the  middle  line  over  the  fourth 
cartilage  and  ending  at  the  centre  of  the  fifth  cartilage  an 
inch  from  the  mid-sternal  line. 

(4)  Left  Border. — From  the  left  end  of  the  base  with  a  con- 
vexity outward  to  the  apex.  It  reaches  its  greatest  distance 
(three  inches)  from  the  sternal  centre  over  the  fourth  space. 

(5)  Lower  Border. — A  line  curved  downward  at  its 
beginning  (at  the  lower  extremity  of  the  right  border)  and 
ending  (at  the  apex),  and  slightly  convex  upward  in  its 
centre  as  it  crosses    the  middle  of  the  ensiform. 

(6)  The  Area  of  Heart  Didlncss. — A  quadrilateral  area  to 
the  left  of  the  median  line  and  below  the  upper  border  of  the 
fifth  cartilage,  nearly  two  inches  in  vertical  and  an  inch  and 
a  half  in  extreme  lateral  measurements.  See  anterior  bor- 
der of  left  lung  below. 

(7)  Tlie  Auricles. — The  Right:  An  "ear-shaped"  area 
facing  to  the  left,  covering  the  first  inch  of  the  third  right 
space  and  cartilage  with  the  portion  of  the  sternum  adjacent 
to  the  latter.      Its  long  axis  measures  about  two  inches  and 


F'K-  58.    Composite  Chest-Heart  Photograph. 

See  statement  with  Fig.  57. 

The  lettering  is  the  same  as  in  the  preceding  figure. 

In  this  case  the  heart  was  in  a  firmly  contracted  condition. 


262  A  MANUAL  OF  ANATOMY. 

is  inclined  from  above  downward  and  outward.  The  Left : 
Is  a  small  oval  space  half  an  inch  by  an  inch,  its  centre  an 
inch  and  a  quarter  to  the  left  of  the  median  line  behind  the 
second  left  space  and  third  cartilage.  Its  long  axis  is 
directed  from  above  downward  and  outward. 

(8)  TJie  aiiricidove utricular  groove  is  indicated  by  a  line 
from  the  right  to  the  left  heart  border,  beginning  on  a  level 
with  the  upper  margin  of  the  fourth  right  and  ending  on  a 
level  with  the  lower  edge  of  the  third  left  cartilage.  This 
line  is  convex  upward  and  crosses  the  middle  of  the  ster- 
num on  a  level  with  the  lower  border  of  the  third  cartilages. 

(9)  The  aortic  area  is  a  little  more  than  an  inch  wide  and 
two  inches  in  length.  It  extends  from  the  upper  border 
of  the  third  to  behind  the  middle  of  the  first  cartilages.  At 
its  beginning  and  ending  its  centre  is  behind  the  median 
hne,  but  in  the  middle  of  its  course  the  artery  is  convex 
toward  the  right. 

( I  o)  Tlie  Area  of  the  Pulmonary  Artery. — About  an  inch 
and  a  quarter  wide  and  an  inch  and  a  half  long  (in  the  photo- 
graph). Begins  on  a  level  with  the  lower  border  of  the 
third,  and  ends  behind  the  middle  of  the  second  left  carti- 
lages. Below,  its  centre  is  half  an  inch,  and  above,  three- 
quarters  of  an  inch,  to  the  left  of  the  median  line. 

(11)  The  superior  vena  cava  is  represented  by  a  vertical 
area  three-fourths  of  an  inch  wide  at  the  right  of  the  aortic 
area,  reaching  from  the  (right  auricle)  right  extremity  of  the 
base  line  upward  to  the  first  intercostal  space,  where  the 
innominate  veins  coalesce. 

(12)  The  outline  of  the  lungs  (in  inspiration)  is  indicated 
by  the  following  lines  : — 

The  apices  of  the  lungs  reach  into  the  base  of  the  neck 
a  distance  of  from  one  and  a  half  to  two  inches  above  the 
first  ribs,  consequently  the  lines  representing  the  apices  of 


UPPER  EXTREMITY  AND   THORAX,  ANTERIOR.      263 

the  lungs  would  begin  over  the  middle  of  the  clavicles, 
pass  upward  and  inward  for  a  distance  of  three-fourths  of 
an  inch  until  over  the  sternal  end  of  the  clavicles,  then 
drawn  downward  and  inward,  crossing  the  sternoclavicular 
articulations,  toward  the  middle  line  of  the  body,  to  meet  at 
the  level  of  the  upper  border  of  the  second  cartilages  (junc- 
tion of  first  and  second  pieces  of  the  sternum).  The 
anterior  borders  of  the  two  lungs  lie  in  contact  (separated 
by  the  pleurae)  from  this  point  to  the  level  of  the  middle 
of  the  sternum  (the  mid-point  between  the  fourth  carti- 
lages). From  here  they  separate,  due  to  the  presence  of  a 
notch  in  the  anterior  border  of  the  left  lung  for  the  accom- 
modation of  the  heart.  The  right  continues  directly  down- 
ward to  the  sternal  end  of  the  sixth  cartilage.  The  left 
turns  outward  and  downward  along  the  upper  border  of  the 
fifth  cartilage  until  it  reaches  a  distance  of  one  and  one-half 
inches  from  the  middle  line,  when  it  turns  downward  to  the 
upper  margin  of  the  sixth  rib  three  inches  from  the  median 
line.  Each  lung  is  divided  into  two  main  lobes  by  the 
great  fissure  and  the  right  has  in  addition  a  third  lobe  cut 
off  by  a  secondary  fissure. 

The  great  fissure  is  indicated  on  the  chest  by  drawing 
a  line  from  the  third  dorsal  spine  obliquely  downward  and 
forward  to  the  sixth  costochondral  articulation,  for  the  left 
side  ;  and  from  the  fourth  dorsal  spine  to  the  seventh  costo- 
chondral joint  on  the  right  side.  The  secondary  fissure, 
on  the  right  side,  is  drawn  from  the  angle  of  the  sixth  to  the 
cartilage  of  the  fourth  rib.  The  lower  border  of  the  lungs 
is  represented  by  a  line  drawn  around  the  chest  diagonally 
from  the  sixth  cartilage  at  the  sternum,  to  the  tenth  dorsal 
spine  behind.  On  the  left  side  this  line  represents  the 
lower  border  also,  but  it  should  be  started  at  a  distance 
of  three  inches  from  the  middle  line.      This  entire  border 


264  A  MANUAL   OF  ANA  TOMY. 

varies,  of  course,  with   the   descent  of  the   lungs  during 
inspiration. 

(13)  The  Line  Indicating  the  Level  of  the  Pleurce. — 
This  is  lower  than  that  of  the  lungs.  It  is  represented 
by  a  line  starting  at  the  sternum  at  the  articulation  of  the 
seventh  cartilage,  and  passes  obliquely  around  the  chest  to 
the  spine  of  the  eleventh  dorsal  vertebrae.  This  line  crosses 
the  lower  border  of  the  ninth  rib  in  the  axillary  line,  and 
behind  is  as  low  as  the  upper  border  of  the  twelfth  rib. 

(14)  TJie  t7'achea  bifurcates  on  a  level  with  the  articu- 
lation between  the  first  and  second  pieces  of  the  sternum. 

(15)  The  internal  mammary  artery  runs  vertically 
downward  behind  the  costal  cartilages  and  intercostal  mus- 
cles one-half  inch  external  to  the  sternal  border  as  low  as 
the  sixth  cartilage,  where  it  divides  into  its  two  terminal 
branches,  the  superior  epigastric  and  musculophrenic. 

DISSECTION. 
Incisions. — i.  In  the  median  line  from  the  top,  to  the  bottom  of  the  sternum. 

2.  From  the  beginning  of  i,  out  along  the  clavicle  to  the  point  of  the 
shoulder  (same  incision  as  2,  page  69). 

3.  From  the  lower  end  of  i,  transversely  around  the  body,  as  far  as  the 
posterior  axillary  line  (same  as  2,  page  435). 

4.  From  the  centre  of  the  clavicle  down  the  front  of  the  arm  to  the  elbow. 
Remove  the  integument  from  the  chest  and  upper  part  of  the  arm. 

The  Superficial  Fascia. 

This  sheet  of  subcutaneous  tissue  covers  the  entire  area. 
It  is  continuous  with  the  similar  fascia  of  the  abdomen, 
neck,  back,  shoulder,  and  arm.  Its  thickness  depends 
upon  the  amount  of  adipose  tissue  present  in  its  meshes. 
Within  the  fascia  are  found  the  subcutaneous  vessels,  nerves, 
and  the  mammary  gland. 

Superficial  Vessels  and  Nerves  and  Origin  of  Platysma. 
At  the  upper  part  of  the  chest  the  origin  of  the  platysma 


F'g-  59-  Composite  Chest-Lungs  Photograph.  [See  Fig.  57  for  explanatory  re- 
marks.]—a,  Manubrium.  6,  Anterior  border  of  right  lung,  c,  Anterior  border  of  left  lung. 
d,  e.  Extent  of  contact  of  these  borders.  /,  Notch  iu  left  lung  for  the  heart.  Corresponds 
to  the  area  of  heart  dullness. 


266  A  MANUAL   OF  ANATOMY. 

will  be  seen  extending  about  an  inch  below  the  border  of 
the  clavicle.  In  this  region,  too,  will  be  found  the  terminal 
filaments  of  the  sternal,  clavicular,  and  (over  the  point  of 
the  shoulder)  the  acromial  nerves  from  the  cervical  plexus.. 
See  page  91. 

Along  the  front  of  the  chest  are  the  terminal  twigs  of  the 
intercostal  nerves,  second  to  sixth  inclusive,  and  perforating 
branches  of  the  internal  mammary  artery.  At  the  side  are 
the  lateral  cutaneous  branches  of  the  intercostal  nerves, 
second  to  sixth  inclusive.  These  perforate  the  fascia  along 
the  mid-axillary  line.  One  large  one,  the  intercostohumeral, 
must  be  saved. 

The  Mammary  Gland. 

The  mammary  gland  is  rudimentary  in  the  male.  In  the 
female  it  varies  greatly  in  size.  Usually  it  covers  a  space 
represented  by  a  circle  whose  centre  is  at  the  nipple  (see 
below),  and  whose  diameter  reaches  from  the  third  to  the 
sixth  ribs  inclusive.  The  nipple  is  usually  over  the  fourth 
intercostal  space,  four  inches  from  the  median  line.  It  is 
surrounded  by  a  darker  area — the  areola — about  one  inch 
in  diameter. 

The  arteries  are  the  intercostal  branches  of  the  internal 
mammary,  through  the  second,  third,  and  fourth  spaces, 
the  long  thoracic  artery,  and  often  an  abnormal  branch 
(external  mammary)  from  the  axillary. 

The  veins  follow  the  arteries. 

The  nerves  are  derived  from  the  fourth,  fifth,  and  sixth 
intercostal  nerves,  and  from  the  terminal  filaments  of  the 
clavicular  branch  of  the  cervical  plexus. 

The  Lymphatics  are  Important. 

The  main  lymphatic  trunks  proceed  to  the  pectoral  and 


Fig.  60.  Superficial  Shoulder,  Anterior. — i,  Deltoid.  2,  Clavicular,  and  3, 
Sternal  portions  of  the  pectoralis  major.  4,  Deep  fascia  of  arm.  5,  Transverse  cervi- 
cal artery.    6,  Clavicle.    7,  Cephalic  vein.    8,  Sternum. 


268  A  MANUAL   OF  ANA  TOMY. 

thence  to  the  axillary  glands.     They  follow  along  the  long 

thoracic  artery. 

DISSECTION. 
Remove  the  superficial  fascia  from  the  same  area  as  the  skin,  leaving  the 
deep  fascia  miinjured  behind. 

The  Deep  Fascia. 

This  is  a  very  thin  layer  covering  the  pectoralis  major. 
Anteriorly  it  is  attached  to  the  front  of  the  sternum,  above 
to  the  clavicle,  externally  it  passes  on  to  the  deltoid  muscle, 
and  below  turns  over  the  lower  border  of  the  pector- 
alis major  and  stretches  across  the  axillary  space  {axillary 
fascia)  to  the  latissimus  dorsi  muscle,  which  it  covers. 
Externally  the  axillary  fascia  passes  into  the  deep  fascia 
covering  the  arm. 

The  axillary  fascia  (and  integument)  is  deeply  hollowed 
when  the  arm  is  extended  to  an  angle  of  45  degrees  with 
the  trunk.  This  is  due  to  the  attachment  of  the  fascia  cov- 
ering the  pectoraHs  minor  muscle.     See  page  270. 

DISSECTION. 

Remove  the  deep  fascia,  cutting  parallel  with  the  fibres  of  the  muscle  it 
covers.  In  turning  down  the  axillary  fascia  be  careful  to  save  the  nerves 
which  will  be  found  coming  out  from  the  axillary  space. 

Clean  the  cephalic  vein  from  the  middle  of  the  arm  to  where  it  disappears 
through  the  costocoracoid  membrane  (see  below),  the  branches  of  the 
acromiothoracic  artery,  and  the  external  anterior  thoracic  nerve. 

Pectoralis  Major.     Fig.  60. 

Origin. — The  clavicular  portion,  from  the  anterior  sur- 
face of  the  inner  half  of  the  clavicle.  The  sternal  portion, 
from  the  anterior  surface  of  the  sternum,  from  the  anterior 
surface  of  the  second  to  sixth  costal  cartilages  inclusive, 
also,  sometimes,  the  first  and  seventh  cartilages,  and  from 
the  aponeurosis  of  the  obliquus  externus  abdominis. 

hisertion. — Into  the  anterior  or  external  lip  of  the  bicipi- 


UPPER  EXTREMITY  AND   THORAX,  ANTERIOR.       269 

tal  ridge,  for  a  distance  of  two  inches  below  the  greater 
tuberosity  of  the  humerus.  The  tendon  of  insertion  is  in 
two  layers,  the  anterior  layer  belonging  to  the  clavicular 
portion  of  the  muscle  ;  the  posterior  layer  to  the  sternocos- 
tal portion.  These  layers  are  open  above  but  joined  below 
along  the  lower  border  of  the  tendon.  The  fibres  of  the 
muscle  (sternocostal)  inserted  into  the  posterior  layer  of  the 
tendon  are  twisted  on  themselves  until  the  lower  fibres  of 
origin  take  the  highest  point  of  insertion,  and  the  highest 
fibres  of  origin  take  the  lowest  point  of  insertion. 

Nerve  Supply. — From  the  anterior  thoracics  :  The  ex- 
ternal thoracic  nerve  arises  from  the  outer  cord  and  enters 
the  muscle  above  the  pectoralis  minor  ;  the  internal  nerve 
comes  from  the  inner  cord  and  pierces  the  minor  to  end  in 
the  major  muscle. 

Action. — (i)  On  the  humerus.  The  muscle  adducts  and 
flexes  the  humerus  if  previously  extended  ;  when  the  arm  is 
at  the  side  it  will  rotate  it  internally  and  draw  it  across  the 
front  of  the  chest  (adduction  and  flexion).  (2)  On  the 
shoulder.  When  the  arm  is  fixed  the  muscle  will  draw  the 
shoulder  downward  and  forward.  (3)  On  the  chest.  When 
the  body  is  supported  on  the  arms  the  pectoral  muscles  sling 
the  chest  between  them.  If  the  arms  are  fixed  upward 
and  forward  the  muscles  will  raise  the  body  (as  in  climbing). 

The  sternocostal  portion  of  the  muscle  may  have  some 
action  in  enlarging  the  chest  in  difficult  respiration,  and  thus 
become  an  accessory  muscle  of  inspiration. 

The  Cephalic  Vein.     Figs.  60,  61. 

(Now  dissected  from  the  middle  of  the  arm  ;  see  below 
for  its  formation  at  the  elbow.) 

The  cephalic  vein  starts  just  above  the  elbow-joint  by 
the  confluence  of  the  median  cephalic  and  the  radial  veins ; 


270  A  MANUAL   OF  ANATOMY. 

it  runs  upward  in  the  groove  at  the  outer  margin  of  the 
biceps  muscle,  then  enters  the  interval  between  the  deltoid 
and  pectoralis  major  muscles,  to  finally  pierce  the  costo- 
coracoid  membrane  in  front  of  the  clavicle  and  empty  into 
the  axillary  vein.  In  the  course  between  the  last  muscles 
it  is  accompanied  by  the  descending  (humeral)  branch  of 
the  acromiothoracic  artery. 


DISSECTION. 
""  Section  the  pectoralis  major  at  its  middle  and  outer  thirds,  and  cut  it  away 
from  the  clavicle.  Raise  the  parts  and  reflect  them.  Notice  the  formation 
and  method  of  insertion  of  the  tendon,  and  the  nerve  and  arterial  supply  to 
the  inner  part  of  the  muscle.  Carefully  expose  the  deep  fascia  (costocor.acoid 
membrane).     The  nerves  and  arteries  exposed  can  now  be  completed. 

The  Costocoracoid  Membrane.      Fig.  6i. 

This  starts  from  the  under  surface  of  the  clavicle  in  two 
layers,  one  in  front,  the  other  behind  the  subclavius  muscle. 
These  two  layers  become  united  along  the  front  of  the 
muscle  and  form  a  single  plane  of  fascia  that  spreads 
downward  to  the  pectoralis  minor  muscle,  inward  to  the 
first  rib  and  cartilage,  and  the  aponeurosis  of  the  first  inter- 
costal space,  and  outward  to  the  coracoid  process.  The 
portion  of  the  membrane  between  the  coracoid  process  and 
the  first  costal  cartilage  is  much  thicker  and  stronger  than 
any  other  part  of  the  membrane,  and  is  known  as  the  costo- 
coracoid lig-ament. 

The  costocoracoid  membrane  is  perforated  by  the 
cephalic  and  acromiothoracic  veins,  the  acromiothoracic 
artery,  the  external  anterior  thoracic  nerve,  and  the  axillary 
lymphatic  trunk. 

The  outward  continuation  of  this  membrane  is  in  the 
shape  of  two  layers  of  thin  fascia  which  enclose  the  pector- 
alis minor  muscle,  unite  at  the  lower  margin  of  the  same, 


Fig.  6i.  Superficial  Dissection  of  Shoulder.  Costocoracoid  Membrane. — 
a,  Platysma  myoides.  b.  Clavicle,  c,  Pectoralis  major,  d.  Deltoid.  The  pectoralis 
major  and  deltoid  muscles  are  separated  so  as  to  show  the  costocoracoid  membrane  and 
the  structures  which  traverse  it.  e.  The  cephalic  vein,  y,  The  costocoracoid  ligament. 
The  branches  of  the  acromiothoracic  artery  are  seen  along  with  the  cephalic  vein. 


272  A  MANUAL  OF  ANATOMY. 

and  become  continuous  with  the  axillary  fascia.  The 
attachment  of  the  lesser  pectoral  (clavipectoral)  fascia  to 
the  axillary  fascia  draws  upward  the  latter,  and  this  ex- 
plains why  it  is  that  the  floor  of  the  axilla  is  so  hollowed 
out  or  concave  externally  (the  pit  of  the  arm).  This  con- 
cavity is  greatest  when  the  arm  is  midway  between  the  side 
of  the  chest  and  right-angle  abduction. 

The  branches  of  the  acromiothoracic  artery  will  be 
found  in  the  interval  between  the  pectorahs  major,  deltoid, 
and  clavicle.  They  are  the  humeral,  acromial,  clavicular,. 
and  thoracic.      Figs.  6o,  6i,  62. 

The  fuuneral  (descending)  is  found  along  with  the  ceph- 
alic vein  in  the  groove  between  the  deltoid  and  pectoralis 
major  muscles,  supplying  both. 

The  acromial  may  be  a  branch  directly  from  the  main 
trunk  or  often  from  the  humeral.  It  supplies  the  region 
about  the  shoulder. 

The  clavicular  branch  is  a  constant  branch  to  the  sub- 
clavius,  but  may  arise  from  the  thoracic  branch. 

The  thoracic  distribution  is  usually,  by  two  or  more 
branches,  to  the  pectoral  muscles  and  side  of  the  chest. 

The  External  Anterior  Thoracic  Nerve. — This  will  be 
found  coming  through  the  costocoracoid  membrane  and 
passing  to  the  pectoralis  major.      Fig.  62. 

DISSECTION. 

Remove  the  costocoracoid  membrane  and  expose  the  subclavius  muscle, 
first  portion  of  the  axillary  artery  and  its  two  branches,  the  accompanying 
vein,  and  cords  of  the  brachial  plexus. 

Clean  the  pectoralis  minor  muscle  and  the  floor  of  the  axilla  external  to 
the  muscle,  saving  the  nerves  and  arteries  found. 

Subclavius.     Fig,  62. 

Origin. — From  the  cartilage  and  first  rib  at  their  point 
of  junction. 


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274  A  MANUAL   OF  ANA  TOMY. 

Insej'tion. — Into  the  middle  third  of  the  lower  surface  of 
the  clavicle,  between  the  conoid  and  rhomboid  ligaments. 

Nerve  Supply. — Supraclavicular,  from  the  first  trunk  of 
the  brachial  plexus  (fifth  and  sixth  nerves). 

Action. — To  depress  and  draw  forward  the  clavicle,  to 
prevent  outward  displacement  of  the  clavicle. 

Pectoralis  Minor.     Fig.  62. 

Origin. — By  three  slips  from  the  anterior  surfaces  and 
upper  borders  of  the  third,  fourth,  and  fifth  ribs  near  their 
cartilages.  From  the  intercostal  aponeurosis  of  the  in- 
cluded spaces. 

Insertion. — Into  the  inner  side  and  tip  of  the  coracoid 
process  of  the  scapula,  and  inner  side  of  the  tendon  of  the 
coracobrachialis  and  biceps  muscle. 

Nerve  Supply. — The  internal  anterior  thoracic  from  the 
inner  cord  (eighth  and  first  dorsal  nerves). 

Action. — (i)  On  the  scapula.  To  depress,  adduct,  and 
draw  forward  the  shoulder.  (2)  On  chest.  If  the  scapula 
is  fixed  it  will  tend  to  spread  the  ribs  and  raise  them,  thus 
assisting  in  inspiration. 

DISSECTION. 

Section  the  pectoralis  minor  near  its  insertion,  turn  the  inner  part  inward 
and  save  the  nerve  and  blood  supply  to  it. 

Complete  the  dissection  of  the  axillary  space,  beginning  vs^ith  the  axillary 
vein,  which  can  be  removed  between  two  ligatures  (one  at  its  beginning  and 
one  at  its  ending),  after  studying  it  carefully  and  noting  its  relations. 

Observe  the  location  of  the  lymphatic  glands,  especially  those  along  the 
long  thoracic  artery  and  axillary  vein. 

Trace  the  branches  of  the  axillary  artery,  the  nerves  contained  in  the 
axilla,  and  clean  the  presenting  surfaces  of  the  subscapularis,  serratus  mag- 
nus,  teres  major,  and  latissimus  dorsi  muscles,  being  sure  to  remove  all  the 
tissue  filling  the  space  between  the  various  muscles. 

The  Lymphatics. 

The  axillary  lymphatics  are  from  ten  to  twelve  in  num- 


UPPER  EXTREMITY  AXD   THORAX,  AXTERIOR.       275 

ber.  They  are  grouped  in  several  sets,  two  of  which  are 
especially  worthy  of  notice.  (i)  The  pectoral  set:  four 
or  five  in  number,  below  the  lower  border  of  the  pectoralis 
major  and  with  the  long  thoracic  artery.  These  receive 
the  drainage  from  the  front  and  side  of  the  chest  (including 
the  mammar}'  gland)  ;  hence  in  inflammatory  or  malignant 
disease  of  the  chest  or  mamma  these  lymphatics  are  first 
affected.  (2)  The  axillary  set :  three  or  four,  located  along 
the  axillary  vein.  These  receive  the  lymph  from  the  upper 
extremity  and  from  the  pectoral  set  of  glands.  They  be- 
come enlarged  in  inflammatory  affections  of  the  extremity, 
or  from  the  chest  by  extension  through  the  first  set.  They 
are  closely  connected  to  the  vein,  especially  in  the  inflamed 
condition.      Their  removal  should  proceed  with  caution. 

The  Axillary  Vein. 

The  axillary  vein  is  formed  by  the  confluence  of  the 
venae  comites  of  the  brachial  artery  and  the  basilic  vein, 
at  the  lower  border  of  the  subscapularis  muscle.  It  takes 
a  course  upward  along  the  inner  side  and  front  of  the  artery 
(overlapping  it  in  front),  to  become  the  subclavian  vein  at 
the  lower  border  of  the  first  rib.  It  receives,  besides  the 
veins  which  unite  to  form  it,  the  veins  corresponding  to  the 
branches  of  the  axillary  artery,  and  the  cephalic  vein, 
which  passes  through  the  costocoracoid  membrane  to 
empty  into  it. 

The  Axillary  Artery.      Figs.  62,  63. 

This  is  the  continuation  of  the  subclavian,  from  the 
lower  border  of  the  first  rib  to  the  lower  border  of  the  teres 
major  muscle.  It  lies  near  the  outer  angle  of  the  axillary 
space.  It  is  div^ided  into  three  portions  by  the  pectoralis 
minor,  that  above,  behind,  and  below  the  muscle. 

The  Relations  of  the  Axillary  Artery. — The  axillaiy 


V 


276  A  MANUAL   OF  ANATOMY. 

vein  lies  to  the  inside  and  a  little  in  front  of  the  artery  for 
its  entire  extent.  Besides  the  vein  there  is  the  internal  an- 
terior thoracic  nerve  to  the  inside  of  the  first  portion  of 
the  artery,  the  inner  cord  of  the  brachial  plexus  for  the 
second,  and  the  ulnar  nerve  for  the  third  part.  These 
nerves  intervene  between  the  artery  and  the  vein.  Also  at 
the  inner  part  of  the  third  portion  is  the  lesser,  and  the  in- 
ternal cutaneous  nerves,  and  the  inner  head  of  the  median. 
On  the  outside,  for  the  first  part,  are  the  cords  of  the 
brachial  plexus  ;  for  the  second  part,  the  outer  cord  of 
the  same,  and  the  coracoid  process  ;  for  the  third  part,  the 
median  and  musculocutaneous  nerves,  the  coracobrach- 
ialis  and  biceps  muscles. 

Behind  the  first  part  is  the  first  intercostal  space  and 
muscle,  second  rib,  and  second  digitation  of  the  serratus 
magnus  muscle,  and  the  posterior  thoracic  nerve.  In  the 
second  part,  posterior  cord  and  first  subscapular  nerve^  and 
the  subscapularis  muscle.  Behind  the  third  part,  the  mus- 
culospiral,  second  and  third  subscapular  and  the  circum- 
flex nerves,  the  subscapularis,  teres  major,  and  latissimus 
dorsi  muscles.  In  front  of  all  parts  of  the  artery,  the  skin, 
superficial  and  deep  fascia,  and  the  pectoralis  major  muscle 
(does  not  cover  the  lower  part  of  the  artery).  In  front  of 
the  first  part,  origin  of  platysma,  cephalic  and  acromio- 
thoracic  artery,  veins  and  branches,  external  anterior  thor- 
acic nerve,  axillary  lymphatic  trunk  and  costocoracoid 
membrane.  Over  the  second  part,  the  pectoralis  minor 
muscle.  In  front  of  the  third  portion,  inner  head  of 
median,  outer  brachial  vena  comes. 
Branches  of  the  Axillary  Artery. 

First  Portion. — {a)  Superior  thoracic.  This  is  a  small 
artery  from  the  inside  of  the  axillary  close  below  the  sub- 
clavius  muscle.      It  passes   to    the  first  intercostal  space 


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278  A  MANUAL  OF  ANATOMY. 

along  the  upper  border  of  the  pectoralis  minor.  {J?)  The 
acromiothoracic.  This  arises  as  a  short  trunk  from  the 
front  of  the  axillary,  j  ust  above  the  pectoralis  minor,  pierces 
the  costocoracoid  membrane,  and  breaks  up  into  three  or 
four  sets  of  branches  ;  the  humeral  (descending),  which 
accompanies  the  cephalic  vein  into  the  groove  between  the 
deltoid  and  pectoralis  major  muscles  ;  the  acromial,  usu- 
ally a  branch  from  the  above,  to  the  region  of  the  point  of 
the  shoulder  ;  the  thoracic,  two  or  three  branches  to  the 
chest  and  pectoral  muscles  ;  the  clavicular,  often  from 
the  thoracic  to  the  subclavius  muscle. 

Second  Portion. — {a)  The  alar  thoracic.  There  may  be 
one  or  several  alar  arteries,  and  they  may  arise  from  the 
axillary  or  from  the  neighboring  branches,  usually  from  the 
long  thoracic.  They  supply  the  glandular  and  adipose 
tissue  in  the  axillary  space.  {U)  The  long-  thoracic  is 
given  off  from  the  inner  side  of  the  axillary  behind  the 
pectoralis  minor,  passes  along  the  lower  border  of  the  same, 
and  is  distributed  to  the  pectoral  muscles,  side  of  chest, 
and  mammary  gland. 

Third  Portion. — {a)  The  subscapular,  the  largest  branch 
of  the  axillary  artery,  arises  from  its  inner  side  just  above 
the  lower  border  of  the  subscapularis  muscle,  passes  down- 
ward and  inward  to  the  chest,  lying  in  the  angle  between 
the  subscapularis,  teres  major,  and  latissimus  dorsi  muscles, 
and  terminating  in  the  serratus  magnus  muscle.  About  one 
inch  from  its  origin  the  artery  gives  off  the  dorsal  artery  of 
the  scapula  {dorsalis  scapidce),  a  large  branch  (really  the 
continuation  of  the  subscapular)  which  winds  backward 
around  the  axillary  (outer)  border  of  the  scapula  to  its 
posterior  surface.  It  passes  through  the  triangle  formed  by 
the  subscapularis,  teres  major,  and  long  head  of  the  triceps 
muscles.    For  rest  of  course  see  page  371.    (/;)  The  anterior 


UPPER  EXTREMITY  AXD  THORAX,  AXTERIOR.       279 

circumflex  is  a  small  branch  from  the  outside  of  the  axillary 
opposite  the  surgical  neck  of  the  humerus,  around  which  it 
turns,  under  the  coracobrachialis  and  biceps  muscles,  to  end 
in  the  deltoid.  At  the  bicipital  groove  it  gives  off  a  branch 
(articular)  which  passes  upward  in  the  groove  to  the 
shoulder-joint,  (r)  The  posterior  circumflex,  nearly  as 
large  as  the  subscapular,  is  given  off  the  back  of  the  axil- 
lary, continues  through  the  quadrilateral  space  formed  by 
the  subscapularis,  teres  major,  long  head  of  triceps,  and 
humerus,  with  the  circumflex  nerve.  For  the  continuation 
of  the  artery  see  page  372.  {d^  The  external  mammary. 
This  is  usually  described  as  an  abnormal  branch,  but  is 
found  so  frequently  that  it  deserves  a  place  with  the  more 
constant  branches  of  the  axillary,  from  which  it  arises  at 
the  lower  margin  of  the  axillar}^  space  and  takes  a  course 
downward,  forward,  and  inward  in  the  subcutaneous  tissue 
to  the  mammar}'  region. 

Subscapularis.      Fig.  63. 

Origin. — From  the  inner  two-thirds  of  the  subscapular 
fossa  on  the  anterior  surface  of  the  scapula,  from  the  lower 
two-thirds  of  the  axillary  border  of  the  same  and  inter- 
muscular septum  between  it  and  the  teres  minor. 

Inscrticvi. — Into  the  lesser  tuberosity  of  the  humerus,  the 
surgical  neck  just  below  it,  and  into  the  capsule  of  the 
shoulder-joint.  The  nerve  supply,  from  the  first  (upper) 
and  third  (lower)  subscapular  nerves. 

Action. — To  rotate  the  humerus  inward  ;  if  the  arm  is 
extended,  to  slightly  adduct  the  humerus.  When  the 
humerus  is  fixed  it  acts  upon  the  scapula  to  turn  it  forward. 

Serratus  Magnus.      Figs.  6^,  76. 

Origiji. — From  the  outer  surfaces  and  upper  margins  of 
the  eight  (or  nine)  upper  ribs  at  their  anterior  and  middle 


280  A  MANUAL   OF  ANATOMY. 

thirds  by  nine  (or  ten)  fleshy  sHps,  two  arising  from  the 
second  rib. 

Insertion. — Into  the  anterior  aspect  of  the  vertebral  bor- 
der and  superior  and  inferior  angles  of  the  scapula. 

Nerve  Supply. — The  posterior  or  long  thoracic  (external 
respiratory  of  Bell),  which  brings  filaments  from  the  fifth, 
sixth,  and  seventh  cervical  nerves. 

Action. — (i)  On  the  scapula.  The  muscle  draws  the 
scapula  forward,  and  owing  to  the  lower  portion  of  the 
muscle  being  longer  than  the  upper,  the  lower  angle  of  the 
scapula  will  be  advanced  farther  than  its  upper  angle,  thus 
producing  a  rotation  of  the  scapula  around  a  central  axis 
perpendicular  to  its  plane  surface.  This  action  is  further 
developed  in  raising  the  arm  to  a  vertical  position,  the 
deltoid  carrying  it  to  a  right  angle,  the  trapezius  and  serra- 
tus  magnus  completing  the  action.  (2)  On  the  ribs.  If 
the  scapula  is  fixed  backward,  the  muscle  would  tend  to 
draw  the  ribs  outward,  and  so  enlarge  the  chest  laterally 
and  aid  inspiration. 

The  Posterior  Thoracic  Nerve.     Figs.  63,  64. 

For  formation,  see  description  of  brachial  plexus,  page  315. 

Appears  in  the  axilla  posterior  to  the  axillary  artery  and 
vein,  continues  downward  across  the  middle  of  the  serratus 
magnus  muscle  to  the  various  digitations  to  which  it  is 
distributed. 

The  Intercostohunieral  Nerve.     Figs.  62,  63,  64. 

This  comes  through  the  second  intercostal  space.  It  is 
the  lateral  cutaneous  branch  of  the  second  intercostal  nerve. 
In  the  floor  of  the  axilla  some  of  its  filaments  interlace  with 
others  from  the  lesser  internal  cutaneous  nerve  to  form  a 
loose  plexus.  The  nerve  is  then  distributed  to  the  integu- 
ment of  the  inner,  upper,  and  posterior  part  of  the  arm. 


Fig.  64.  Dissection  OF  Brachial  Plexus. — i,  Phrenic  nerve.  2,  Fifth  C.  3,  Sixth  C. 
4,  Seventh  C.  5,  Eighth  C.  6,  First  D.  7,  Subclavian  nerve.  8,  Upper  trunk.  9,  Supra- 
scapular nerve.  10,  First  subscapular  nerve.  11,  External  anterior  thoracic  nerve.  12,  Cir- 
cumflex nerve.  13,  Third  subscapular  nerve.  14,  Musculocutaneous  nerve.  15,  Median 
nerve.  16,  Lower  trunk.  The  middle  trunk  is  formed  by  the  continuation  of  the  seventh 
nerve  (4).  17,  Long  thoracic  nerve.  18,  Long  subscapular  nerve.  19,  Ulnar  nerve.  20,  In- 
ternal cutaneous.  21,  Intercostohumeral.  22,  Lesser  internal  cutaneous.  23,  Internal  anterior 
thoracic. 


282  A  MANUAL   OF  ANA  TO  MY. 

The  lateral  cutaneous  branches  of  the  third,  fourth^ 
fifth,  and  sixth  intercostal  nerves  may  be  found  as  they 
appear  along  the  side  of  the  chest  after  coming  through  the 
intercostal  muscles.  The  first  one  or  two  usually  help  to 
form  a  loose  plexus  with  the  intercostohumeral  nerve. 
These  nerves  decrease  in  size  from  above  downward.  The 
third  is  usually  distributed  to  a  small  part  of  the  integu- 
ment of  the  inner  side  of  the  arm  and  axilla,  the  others  to 
the  integument  of  the  side  of  the  chest. 

(The  description  of  the  brachial  plexus  will  be  delayed 
until  the  dissection  of  the  neck  has  proceeded  far  enough 
to  permit  removal  of  the  clavicle,  when  the  entire  extent  of 
the  plexus  will  be  uncovered.) 

DISSECTION. 
Incisions. — (l)  Continue  the  median  incision  to  the  wrist. 
(2)  Make  two  short  transverse  cuts  at  the  lower  end  of  (i). 
Reflect  the  skin  from  the  arm  and  forearm,  saving  the  superficial  nerves 
and  veins. 

The  Superficial  Fascia. 

This  is  usually  a  thin  layer,  but  may  be  thickened  by  the 
presence  of  adipose  tissue  over  the  lower  part  of  the  fore- 
arm and  hand.  In  the  hand  the  superficial  fascia  consists 
of  fatty  granules  between  the  palmar  fascia  and  the  skin. 
In  the  superficial  fascia  ramify  the  subcutaneous  vessels 
and  nerves. 

The  Superficial  Veins  of  the  Arm  and  Porearm.     Fig. 

65. 
On  the  outer  side  of  the  forearm  is  the  radial  vein ;  in 
front,  the  median  ;  at  the  inner  side,  two,  the  anterior  and 
posterior  ulnar,  which  unite  to  form  the  common  ulnar 

at  the  elbow.      These  pass  up  to  the  elbow,  where  the  an- 
terior and  posterior  ulnar  unite  to  form  the  common  ulnar, 


UPPER  EXTREMITY  AND  THORAX,  ANTERIOR.       283 

and  the  median  receives  the  deep  median  vein  from  the  in- 
terior of  the  forearm  and  divides  into  the  median  cephalic 
and  median  basilic.  The  deep  median  vein  is  formed  by 
the  venfe  comites  of  the  ulnar,  radial  recurrent,  and  mus- 
cular arteries. 

The  median  cephalic  joins  the  radial  vein  to  form  the 
cephalic,  which  passes  upward  in  the  groove  at  the  outer 
border  of  the  biceps  muscle. 

The  median  basilic  joins  with  the  common  ulnar  to 
form  the  basilic,  which  ascends  in  the  inner  brachial  groove, 
pierces  the  deep  fascia  in  the  middle  and  lower  thirds  of  the 
arm,  and  terminates  as  one  of  the  tributaries  forming  the 
axillary  vein. 

The  Superficial  Nerves.      Figs.  62,  63,  65. 

These  are,  on  the  inside  of  the  arm,  branches  of  the 
intercostohumeral,  lesser  internal  cutaneous,  internal  cuta- 
neous ;  on  the  outside,  the  cutaneous  branches  of  the  cir- 
cumflex and  the  superior  external  cutaneous  branch  of  the 
musculospiral. 

In  the  forearm  there  are,  on  the  inside,  the  anterior  divi- 
sion of  the  internal  cutaneous,  which  reaches  to  the  wrist  ; 
on  the  outer  side,  the  external  cutaneous  branch  of  the 
musculocutaneous,  which  is  distributed  as  low  as  the  ball 
of  the  thumb. 

The  Deep  Fascia.      Figs.  61,  65. 

The  deep  fascia  of  the  arm  and  forearm  encases  the 
muscles  like  a  tight  sleeve,  forming  their  compartments  and 
fixing  them  in  position.  Above  it  is  continuous  with  the 
deep  fascia  covering  the  deltoid,  pectoralis  major,  teres 
major,  latissimus  dorsi,  and  axillary  space.  Through  these 
extensions  it  passes  to  the  spine  and  acromion  process  of 
the  scapula  and  the  clavicle.      Below,  the  fascia  is  attached 


284  A  MANUAL   OF  ANATOMY. 

about  the  wrist  by  means  of  thickened  portions  called  an- 
nular ligaments. 

At  the  elbow  the  fascia  is  united  to  all  the  bony  points. 
Behind,  to  the  olecranon,  and  here  it  receives  the  fibrous 
expansion  of  the  tendon  of  the  triceps  muscle.  At  the 
sides,  to  the  humeral  condyles,  and  by  means  of  the  inter- 
muscular septa  to  the  condyloid  ridges.  In  front,  it  receives 
the  fascial  prolongation  of  the  bicipital  tendon,  and  is  pierced 
for  the  deep  median  vein. 

The  intermuscular  septa  in  the  arm  separate  the  anterior 
from  the  posterior  muscles.  In  the  anterior  compartment 
are  the  biceps,  coracobrachialis,  brachialis  anticus,  origin 
of  the  supinator  longus,  and  the  extensor  carpi  radialis 
longior.      In  the  posterior  is  the  triceps  muscle. 

In  the  forearm  the  intermuscular  septa  are  especially 
well-marked  and  appear  as  "  white  lines,"  indicating  the 
separations  between  the  various  muscles  and  forming 
guides  to  the  arteries. 

DISSECTION. 
Remove  the  superficial  veins  and  the  deep  fascia  to  just  below  the  elbow. 
Leave  the  insertion  of  the  biceps  into  the  deep  fascia. 
Complete  the  dissection  of  the  parts  exposed. 

Coracobrachialis.      Fig.  62. 

Origin — From  the  tip  of  the  coracoid  process  of  the 
scapula  with  the  short  head  of  the  biceps. 

Insertion. — Into  the  middle  third  of  the  inner  border  of 
the  humerus  for  a  distance  of  two  inches. 

Nerve  Supply. — By  the  musculocutaneous,  which  usually 
passes  through  the  muscle.  The  nerve  filaments  come 
from  the  seventh  cervical  nerve. 

Action. — It  is  an  adductor  and  flexor  of  the  arm  ;  helps 
to  hold  the  humerus  against  the  scapula. 


UPPER  EXTREMITY  AND  THORAX,  ANTERIOR.       285 

Biceps.      Figs.  62,  63. 

Origin. — By  a  long  tendinous  head  from  the  top  of  the 
glenoid  cavity  of  the  scapula,  by  a  shorter  muscular  head 
from  the  coracoid  process  of  the  same  bone. 

The  former  tendon  passes  over  the  top  of  the  head  of  the 
humerus  within  the  capsular  ligament  of  the  shoulder,  and 
blends  with  the  glenoid  ligament,  and  the  latter  has  a  com- 
mon origin  with  the  coracobrachialis  muscle. 

Insertion. — By  the  broad  expansion  into  the  deep  fascia 
of  the  forearm.  By  the  tendon  into  the  posterior  margin 
of  the  bicipital  tuberosity  of  the  radius. 

Nerve  Supply. — From  the  musculocutaneous,  which 
brings  fibres  from  the  sixth  and  seventh  cervical  nerves. 

Action. — (i)  It  is  a  feeble  flexor  and  adductor  of  the 
arm.  Serves  to  retain  the  head  of  the  humerus  in  the 
glenoid  cavity.  (2)  On  the  forearm.  A  strong  flexor 
of  the  forearm.  If  the  forearm  has  been  pronated  the 
biceps  acts  as  a  strong  supinator,  the  strength  of  its  action 
of  supination  increasing  until  it  is  the  strongest  when  the 
forearm  is  at  right  angles  with  the  arm. 

Brachialis  Anticus.      Figs.  63,  dj. 

Origin. — From  the  anterior  surface  of  the  shaft  of  the 
humerus  below  the  insertion  of  the  coracobrachialis  and 
deltoid  (the  latter  it  embraces),  and  from  the  anterior  sur- 
face of  the  internal  intermuscular  septum. 

Insertion. — The  rough  surface  at  the  front  and  inside  of 
the  base  of  the  coronoid  process  of  the  ulna. 

Nerve  S?tpply. — By  the  musculocutaneous  in  front  and 
the  musculospiral  behind.  The  sixth  and  seventh  cervical 
nerves  supply  the  filaments. 

Action. — To  flex  the  forearm  upon  the  arm,  or  the 
reverse. 


286  A  MANUAL  OF  ANATOMY. 

The  Brachial  Artery.      Figs.  62,  63,  6^. 

The  brachial  artery  is  the  continuation  of  the  axillary 
from  the  lower  border  of  the  teres  major  to  half  an  inch 
below  the  bend  of  the  elbow,  where  it  divides  into  the  radial 
and  ulnar  arteries. 

Relations. — On  the  outside  :  The  coracobrachialis,  bi- 
ceps (which  slightly  overlaps  the  artery  in  front),  and  the 
median  nerve  (at  the  upper  part). 

The  inner  border  of  these  muscles  is  the  sure  guide  to 
the  artery. 

The  median  nerve,  though  formed  at  the  outside  of  the 
artery  above,  crosses  in  front  (usual)  or  behind  (unusual) 
the  artery  to  its  inside  at  the  elbow.  One  of  the  accom- 
panying veins  is  to  the  outside. 

Behind  :  The  brachial  rests  upon  the  triceps,  tendon  of 
the  coracobrachialis  and  brachialis  anticus  muscles.  It  may 
have  the  median  nerve  behind  its  middle. 

At  the  inside  is  the  other  accompanying  vein.  These 
venae  comites  are  joined  by  frequent  cross  branches.  The 
basilic  vein  takes  a  course  upward  at  the  inside  of  the 
artery  but  separated  from  it  by  the  deep  fascia  in  the  lower 
part  of  its  course. 

The  ulnar  and  internal  cutaneous  nerves  are  at  some 
little  distance  from  the  upper  part  of  the  artery,  and  in  its 
lower  two-thirds  have  no  direct  relation  to  it. 

In  front :  The  brachial  is  covered  by  the  integument, 
two  layers  of  fascia,  and  the  inner  border  of  the  biceps 
muscle.  The  median  nerve  is  in  close  relation  to  the  artery 
and  crosses  its  front  about  the  middle  (usual).  At  the 
elbow  the  brachial  has  the  median  basilic  vein  in  front  of  it, 
and  separated  from  it  by  the  bicipital  fascia.  It  lies  be- 
tween the  tendon  of  the  biceps  at  the  outside  and  the 
median  nerve  at  the  inside. 


UPPER  EXTREMITY  AND  THORAX,  ANTERIOR.       287 

Brandies  of  tJie  Bracliial. 

(i)  The  superior  profunda.  This  is  the  largest  branch 
of  the  brachial.  It  arises  from  the  posterior  surface  of  the 
artery,  takes  a  course  downward  ;  then  with  the  musculo- 
spiral  nerve,  downward  and  outward  through  the  musculo- 
spiral  groove  to  terminate  by  anastomosing  with  the  radial 
recurrent  at  the  outer  side  of  the  arm  in  the  space  between 
the  brachialis  anticus  and  the  supinator  longus.  Besides 
the  muscular  branches  it  gives  off  the  ascending  and  articu- 
lar, which  will  be  found  in  the  dissection  of  the  posterior  of 
the  arm. 

(2)  The  inferior  profunda  is  given  off  the  inside  of 
the  brachial  opposite  the  insertion  of  the  coracobrachialis. 
It  often  arises  with  the  superior  profunda  as  a  common 
trunk  from  the  brachial.  It  takes  a  course  downward  and 
inward  with  the  ulnar  nerve  to  get  behind  the  internal  con- 
dyle and  terminates  in  an  anastomosis  with  the  posterior 
ulnar  recurrent  and  anastomotica  magna  arteries. 

(3)  The  nutrient.  This  small  branch  is  given  off  at  the 
lower  part  of  the  insertion  of  the  coracobrachialis  and 
enters  the  nutrient  foramen  of  the  humerus. 

(4)  Muscular  branches  are  supplied  to  the  adjacent  mus- 
cles and  vary  from  six  to  eight  in  number. 

(5)  The  anastomotica  magna.  This  is  from  the  inside 
of  the  brachial  from  one  to  two  inches  above  the  bend  of 
the  elbow.  Its  course  is  inward,  and  at  the  inner  border  of 
the  arm  it  divides  into  two  branches  :  {a)  the  anterior 
which  is  smaller  than  the  posterior,  and  descends  between 
the  brachialis  anticus  and  pronator  radii  teres  to  anastomose 
at  the  inside  of  the  elbow  with  the  anterior  recurrent  ulnar  ; 
{b)  the  posterior,  which  continues  backward  around  the 
inner  side  of  the  arm,  anastomoses  with  the  inferior  pro- 
funda and  posterior  recurrent  ulnar  arteries,  and  terminates 


288  A  MANUAL   OF  ANATOMY. 

(usually)  by  uniting  with   the  articular   branch   of  the  su- 
perior profunda  to  form  an  arch  above  the  olecranon  fossa. 
The  veins.     These  are  venae  comites,  accompanying  the 
arteries  above  and  opening  into  the  brachial  veins. 

The  Nerves.      Figs.  63,  64,  65. 

(i)  The  musculocutaneous  nerve.  This  is  the  direct 
continuation  of  the  outer  cord  of  the  brachial  plexus.  It 
passes  through  the  coracobrachiahs  muscle,  then  between 
the  biceps  and  brachialis  anticus  ;  appearing  at  the  outer 
border  of  the  tendon  of  the  biceps,  it  pierces  the  deep  fascia 
over  the  elbow  and  becomes  the  cutaneous  nerve  to  the 
outer  side  of  the  front  of  the  arm.  In  its  course  through 
the  arm  the  musculocutaneous  supplies  the  coracobrachialis, 
biceps,  and  brachialis  anticus. 

(2)  The  median  nerve  is  formed  by  a  branch  from  the 
outer  and  inner  cords  of  the  brachial  plexus,  which  unite  at 
the  outer  side  of  the  axillary  artery  ;  the  nerve  passes  down 
the  arm  to  reach  the  inner  side  of  the  brachial  artery  in 
front  of  the  elbow,  having  crossed  the  middle  of  the  artery 
in  front  or  behind  it. 

The  median  nerve  has  no  branches  in  the  arm,  but  just 
above  the  bend  of  the  elbow  it  gives  off  the  articular  branch 
to  the  joint. 

(3)  The  ulnar  nerve  continues  the  inner  cord  down  the 
inside  of  the  arm,  is  joined  by  the  inferior  profunda  artery 
about  its  middle,  and  disappears  behind  the  internal  condyle. 
An  articular  branch  is  furnished  to  the  elbow-joint  behind 
the  condyle. 

(4)  The  internal  cutaneous.  This  comes  from  the  inter- 
nal cord,  descends  along  the  inner  side  of  the  arm,  pierces 
the  deep  fascia  above  the  elbow,  divides  into  an  anterior 
and  posterior  branch.     The  anterior   continues  down  the 


Fig-  65.  Superficial  Forearm  and  Hand.— i,  Radial  vein.  2,  Median  cephalic. 
These  two  unite  to  form  the  cephalic  vein.  3,  Median  vein.  4,  Cutaneous  branch  of  musculo- 
cutaneous nerve  (the  external  cutaneous).  5,  Basilic  vein.  6,  Internal  condyle.  7,  Ulnar 
veins.  8,  Median  basilic  vein.  9,  Internal  cutaneous  nerves.  10,  Deep  fascia  of  forearm. 
II,  Outer  portion  of  palmar  fascia.  12,  Annular  ligament  (position  of).  13,  Inner  portion  of 
palmar  fascia,  and  the  palmaris  brevis  muscle.  14,  Middle  portion  of  palmar  fascia.  13,  The 
superficial  transverse  ligament  of  the  fingers  (Fibers  of  Gerdyi.  The  division  of  the  central 
portion  of  the  palmar  fascia  into  its  fasciculi  and  the  position  of  the  digital  vessels  and 
nerves  is  shown.  16,  Digital  nerve  to  little  finger.  17,  18,  19,  20,  21,  22,  Collateral  digital 
nerves  and  vessels. 


Fig.  66.  Dissection  of  Forearm  and  Hand. — i.  Tendon  of  biceps  muscle.  2,  Brachial 
artery  at  point  of  bifurcation.  3,  Radial  recurrent  artery.  4,  Brachioradialis  or  supinator 
longus.  5,  Radial  nerve.  6,  Tendon  of  pronator  radii  teres.  7,  Radial  artery.  8,  Flexor 
carpi  radialis  muscle.  9,  Median  nerve.  10,  Flexor  longus  pollicis.  11,  Superficial  volar 
artery.  12,  Tendon  of  extensor  ossis  metacarpi  pollicis.  13,  Abductor  pollicis.  14,  Outer 
head  of  flexor  brevis  pollicis.  15,  The  digital  branches  of  the  median  nerve.  16,  Digital 
arteries  to  thumb  and  index  finger.  17,  External  lunibrical  muscle.  18,  Adductor  pollicis 
muscle.  19,  Vaginal  ligaments  of  the  sheaths  of  the  long  flexor  tendons.  20,  Tendon  of  the 
flexor  sublimis  digitorum.  21,  Tendon  of  the  flexor  profundus  digitorum.  22,  The  three 
inner  lumbrical  muscles.  23,  Digital  arteries.  24,  Ulnar  digital  nerves.  25,  Abductor 
minimi  digiti.  26,  Superficial  palmar  arch.  27,  Flexor  brevis  minimi  digiti.  28,  The  slender 
nerve  which  passes  from  the  ulnar  to  the  median.  29,  The  deep  communicating  from  the 
ulnar  artery  to  the  radial  to  form  the  deep  palmar  arch.  30,  The  anterior  annular  ligament. 
31,  The  ulnar  nerve.  32,  The  ulnar  artery.  33,  Palmaris  longus  muscle.  34,  Flexor  sublimis 
digitorum.  35,  Flexor  carpi  ulnaris.  36,  Median  nerve.  37,  Internal  condyle  of  humerus. 
38,  The  anastomotica  magna  artery  lying  upon  the  brachialis  anticus  muscle  and  dividing 
into  its  two  terminal  branches. 

19 


290  A  MANUAL  OF  ANATOMY. 

inner  side  of  the  front  of  the  forearm  to  the  wrist,  the 
posterior  passes  backward  to  a  similar  distribution  to  the 
posterior  surface  of  the  forearm. 

The  triceps  muscle  shows  at  the  inside  of  the  arm  and 
should  be  cleaned,  and  the  musculospiral  nerve  and  the 
superior  profunda  artery  traced  between  its  two  lower 
heads. 

(5)  The  musculospiral  nerve.  This  nerve  is  the  direct 
continuation  of  the  posterior  cord.  It  is  found  first  behind 
the  axillary,  then  to  the  inner  side  of  it  and  the  brachial 
artery,  and  disappears  with  the  superior  profunda  artery  by 
entering  the  musculospiral  groove  or  canal  between  the  two 
lower  heads  of  the  triceps  muscle. 

DISSECTION. 
Remove  the  deep  fascia  from  the  forearm  as  low  as  the  annular  ligament 
of  the  wrist. 

Carefully  clean  the  following  structures : — 

Pronator  Radii  Teres.     Fig.  66. 

Origm. — By  the  common  tendon  from  the  lower  half- 
inch  of  the  internal  condyloid  ridge  and  the  internal  con- 
dyle, for  the  upper  head  ;  from  the  inner  margin  of  the 
coronoid  process  of  the  ulna,  by  the  lower  and  smaller  head  ; 
also  from  the  intermuscular  septum  between  it  and  the 
flexor  carpi  radialis. 

Note. — It  will  be  stated  here  for  once,  to  save  repetition,  that  all  the  mus- 
cles arising  from  the  internal  condyle  by  the  common  tendon  also  arise  from 
the  intermuscular  septum  between  each  other. 

Insertion. — Into  the  rough  oval  impression  on  the  outer 
surface  of  the  radius  at  its  middle. 

Nerve  Supply. — By  the  median,  which  passes  between  its 
two  heads.  These  filaments  come  from  the  sixth  cervical 
nerve. 


UPPER  EXTREMITY  AND  THORAX,  ANTERIOR.       291 

Action. — To  pronate  the  forearm  ;  to  aid  in  flexion  of 
the  forearm.  This  muscle  is  a  valuable  accessory  to  the 
flexors  of  the  elbow-joint. 

Flexor  Carpi  Radialis.     Fig.  66. 

Origin. — By  the  common  tendon,  from  the  internal  con- 
dyle of  the  humerus.     (See  note  above.) 

Insertion. — Into  the  base  of  the  second  metacarpal  bone. 
The  tendon  grooves  the  trapezium  upon  its  inner  side  and 
passes  superficial  and  external  to  the  central  compartment 
of  the  annular  ligament. 

Nerve  Supply. — The  median,  by  filaments  from  the  sixth 
cervical  nerve. 

Actions. — To  flex  the  wrist  and  slightly  abduct  the  wrist, 
to  pronate  and  feebly  flex  the  forearm. 

Palmaris  Longus.      Fig.  66. 

Origiji. — Same  as  the  flexor  carpi  radialis.  (See  note 
above.) 

Insertion. — Into  the  anterior  annular  ligament  and  central 
portion  of  the  palmar  fascia. 

Nerve  Supply. — The  median  from  the  eighth  cervical 
nerve. 

Action. — Tensor  of  palmar  fascia,  feeble  flexor  of  wrist 
and  forearm. 

The  Plexor  Carpi  Ulnaris.     Fig.  66. 

Origin. — By  the  common  tendon  from  the  internal  con- 
dyle (see  note),  by  a  second  head  from  the  internal  surface 
of  the  olecranon  and  the  upper  two-thirds  of  the  posterior 
ridge  of  the  ulna. 

Insertion. — Into  the  pisiform  bone,  hook  of  the  unciform, 
and  base  of  the  fifth  metacarpal  bone. 


292  A  MANUAL  OF  ANATOMY. 

Nerve  Supply. — Through  the  ulnar  nei've  b}'  filaments 
from  the  eighth  cervical  and  first  thoracic  nerves. 

Action. — It  is  a  flexor  and  adductor  of  the  wrist  and  a 
weak  flexor  of  the  forearm. 

Supinator  long-US.     {Brachioradialis^     Fig.  67. 

Be  sure  to  carry  the  dissection  of  this  muscle  to  its  origin  ; 
save  the  nerves  and  arteries  found. 

Origin. — From  the  upper  two-thirds  of  the  external  con- 
dyloid ridge,  from  the  external  intermuscular  septum  of 
the  deep  fascia  of  the  arm. 

Insertion. — Into  the  base  of  the  styloid  process  of  the 
radius. 

Nerve  Supply. — The  musculospiral  from  the  sixth  cer- 
vical nerve. 

Action. — Primarily  it  is  a  flexor  of  the  forearm,  second- 
arily a  pronator  in  complete  supination  of  the  forearm, 
and  has  a  slight  action  of  supination  only  when  the  arm 
is  fully  pronated. 

The  Anterior  Elbow  Space.     Fig.  66. 

The  hollow  in  front  of  the  elbow  is  bounded  on  the  out- 
side by  the  supinator  longus,  on  the  inside  by  the  pronator 
radii  teres.      Its  floor  is  formed  by  the  brachialis  anticus. 

From  without  inward  is  found  the  musculospiral  nerve 
(dividing  into  its  radial  and  posterior  interosseous  branches), 
radial  recurrent  artery,  musculocutaneous  nerve  (under 
the  outer  margin  of  the  biceps),  the  tendon  of  the  biceps 
muscle,  the  brachial  artery  and  its  terminal  branches,  the 
ulnar  and  radial,  and  their  accompanying  veins,  the  median 
nerve  and  its  muscular  branches,  and  the  anastomosis 
between  the  anterior  branch  of  the  anastomotica  magna  and 
anterior  ulnar  recurrent. 


UPPER  EXTREMITY  AND  THORAX,  ANTERIOR.       203 

DISSECTION. 
Trace  the  radial  nerve  to  the  posterior  margin  of  the  tendon  of  the  supinator 
longus    (brachioradiaHs).     The    radial    artery  until  it  disappears   under   the 
extensor   tendons  of  the  forearm,  and    its   branches   in    the    forearm.     The 
ulnar  artery  to  the  wrist,  and  its  branches. 

The  Radial  Nerve,     Fig.  66. 

The  anterior  branch  of  the  musculospiral  nerve.  It 
descends  behind  the  inner  portion  of  the  supinator  longus 
muscle,  until  at  the  lower  part  of  the  muscle  it  passes 
backward  to  the  posterior  surface  of  the  thumb  and  hand. 

The  Posterior  Interosseous  Nerve. 

This  is  the  posterior  branch  of  the  musculospiral  nerve 
and  disappears  from  the  front  of  the  elbow  by  passing  into 
the  substance  of  the  supinator  brevis  muscle. 

The  Radial  Artery.     Figs.  66,  67. 

This  is  the  outer  branch  of  bifurcation  of  the  brachial, 
the  direction  of  which  it  continues.  The  portion  of  the 
artery  that  lies  in  the  forearm  extends  from  below  the 
elbow  to  the  wrist,  where  the  artery  passes  posteriorly 
under  the  extensor  tendons  of  the  thumb. 

Its  course  is  outward  and  downward,  between  the  prona- 
tor radii  teres  and  the  supinator  longus  (brachioradiaHs) 
(the  latter  of  which  overlaps  the  artery  in  front),  then 
between  the  tendons  of  the  flexor  carpi  radialis  and  the 
supinator  longus.  The  artery  is  indicated  by  a  line  drawn 
from  just  below  the  centre  of  the  elbow  to  the  inner  side 
of  the  styloid  process  of  the  radius.  The  radial  nerve  is 
at  the  radial  side  of  the  artery  for  the  upper  two-thirds  of 
its  course,  but  not  in  close  relation  with  it,  and  is  not  seen 
in  ligation  of  the  artery. 

The  artery  rests  upon  the  tendon  of  the  biceps,  supinator 


294  A  MANUAL   OF  ANA  TOMY. 

brevis,  pronator  radii  teres,  flexor  sublimis  digitorum,  flexor 
longus  poUicis,  and  pronator  quadratus  muscles,  and  the 
lower  end  of  the  radius. 

The  accompanying  veins  are  on  the  outer  and  inner  sides 
of  the  artery.  While  the  artery  is  overlapped  by  muscles 
in  the  upper  part  of  its  course,  it  is  only  covered  by  the 
fascia  and  skin  in  the  lower  two-thirds. 

Branches  of  the  Radial  Artery. 

(i)  Eadial  recurrent.  This  is  a  large  branch  from  the 
outer  side  of  the  artery  below  its  origin.  It  passes  out- 
ward, supplying  branches  to  the  supinator  longus,  extensor 
carpi  radialis  longior  and  brevior,  and  supinator  brevis, 
then  turns  upward  between  the  supinator  longus  (brachio- 
radialis)  and  brachialis  anticus  to  terminate  in  branches  to 
these  muscles  and  by  anastomizing  with  branches  from  the 
superior  profunda  artery.  (2)  Muscular.  To  the  sur- 
rounding muscles.  (3)  Anterior  carpal.  A  very  small 
branch  to  the  front  of  the  carpus.  (4)  Superficial  volar. 
Variable  in  size  and  occurrence.  Usually  a  small  branch 
to  the  base  of  the  thumb  muscles,  and  terminating  in  them  ; 
at  other  times  a  larger  branch  that  crosses  beyond  the 
thumb  to  anastomose  with  the  ulnar  to  form  the  superficial 
palmar  arch.  For  the  remaining  branches  see  back  of 
hand. 

DISSECTION. 

Divide  the  flexor  carpi  radialis,  palmaris  longus,  and  flexor  carpi  ulnaris 
where  they  become  tendinous,  and  the  pronator  radii  teres  at  its  outer  and 
middle  thirds. 

Clean  the  flexor  sublimis  digitorum,  the  anterior  surface  of  the  supinator 
brevis,  the  upper  and  lower  thirds  of  the  ulnar  artery,  and  the  ulnar  nerve 
from  the  internal  condyle  to  the  wrist. 

Flexor  Sublimis  Dig-itorum.      Fig.  66. 

Origin. — (i)  From  the  internal  condyle  of  the  humerus 
and  internal  lateral  ligament  of  the  elbow-joint.     (2)  From 


UPPER  EXTREMITY  AND  THORAX,  ANTERIOR.       295 

the  inner  margin  of  the  coronoid  process  of  the  ulna.  (3) 
From  the  oblique  ridge  on  the  front  of  the  upper  part  of 
the  radius. 

See  note,  page  290. 

Insertion. — By  four  tendons  which  perforate  the  tendons 
of  the  long  flexor  muscle  (as  described  in  the  dissection  of 
the  hand,  see  page  311),  and  are  attached  to  the  sides  of  the 
the  second  set  of  phalanges  of  the  four  fingers. 

Nerve  Supply. — The  median  (seventh  and  eighth  cervical 
and  first  thoracic  nerves). 

Action. — Beginning  from  below,  the  muscle  will  flex  the 
second,  then  the  first  set  of  phalanges,  then  the  hand,  and 
perhaps  slightly  the  forearm. 

DISSECTION. 
Remove  the  flexor  sublimis  digitorutn  from  its  radial  attachment  and  turn  it 
inward,  cleaning  the  median  nerve,  interosseous  arteries,  and  nerve.     Finish 
the  ulnar  artery  ;   clean  the  last  layer  of  muscles. 

The  Ulnar  Artery.      Fig.  6^. 

This  is  the  other  branch  of  brachial  bifurcation  just  below 
the  elbow.  It  passes  inward  and  downward  under  all  the 
superficial  layer  of  muscles,  and  also  between  the  flexor 
sublimis  and  profundus  digitorum.  At  the  middle  and 
upper  thirds  of  the  forearm  it  bends  directly  downward  and 
enters  the  wrist  over  the  annular  ligament  at  the  outer  side 
of  the  pisiform  bone. 

The  course  of  the  lower  two-thirds  of  the  artery  is  indi- 
cated by  a  line  from  the  internal  condyle  to  the  outer  side 
of  the  pisiform  bone.  The  guide  to  the  artery  is  the  inter- 
muscular septum  between  the  flexor  sublimis  digitorum  and 
the  flexor  carpi  ulnaris.  The  artery  has  two  accompanying 
veins. 

Relations. — In  front :    Pronator   radii  teres,  flexor  carpi 


296  A  MANUAL  OF  ANA  TOMY. 

radialis,  palmaris  longus,  flexor  sublimis  digitorum,  for 
the  upper  half.  In  the  lower  half,  and  for  the  entire 
course,  by  the  skin  and  fasciae. 

Internally  :  The  flexor  carpi  ulnaris.  The  ulnar  nerve  is 
close  to  the  ulnar  side  of  the  artery  for  the  lower  two- 
thirds  of  its  course  in  the  forearm. 

Outside  :  The  tendons  of  the  flexor  sublimis  digitorum 
for  the  lower  two-thirds.  Behind :  Brachialis  anticus, 
flexor  profundus  digitorum. 

Brandies  of  the  Ulnar  Artery. 

(i)  Recurrent:  {a)  The  anterior.  Usually  a  branch 
from  the  posterior  recurrent  may  arise  from  the  ulnar  just 
after  its  origin.  It  ascends  behind  the  pronator  radii 
teres  to  anastomose  upon  the  brachialis  anticus  with  the 
anterior  branch  of  the  anastomotica  magna  and  the  in- 
ferior profunda,  {b^  The  posterior  recurrent.  A  larger 
artery  than  the  anterior  (which  is  usually  derived  from 
it)  from  the  inner  side  of  the  ulnar.  It  runs  upward  upon 
the  flexor  profundus  digitorum  to  behind  the  internal 
condyle,  and  between  the  two  heads  of  the  flexor  carpi 
ulnaris  muscle,  and  terminates  by  an  anastomosis  with  the 
inferior  profunda,  posterior  branch  of  the  anastomotica 
magna,  and  interosseous  recurrent.  Behind  the  internal 
condyle  it  is  close  to  the  ulnar  nerve. 

(2)  Coinnion  interosseous  :  This  is  a  large  branch  from 
the  outer  part  of  the  ulnar,  about  half  an  inch  long,  which 
passes  backward  and  divides  into  the  anterior  and  posterior 
interosseous  arteries,  {a)  The  anterior  interosseous  con- 
tinues the  direction  of  the  main  trunk  down  the  front  of  the 
interosseous  membrane,  between  the  flexor  longus  poUicis 
and  flexor  profundus  digitorum,  to  the  upper  margin  of  the 
pronator    quadratus  muscle,   behind  which    it  disappears. 


UPPER  EXTREMITY  AND  THORAX,  ANTERIOR.       297 

There  are  two  veins  with  the  artery,  and  the  interosseous 
branch  of  the  median  nerve. 

The  anterior  interosseous  artery  supplies  numerous 
branches  to  the  adjacent  muscles,  and  one  which  follows 
the  median  nerve  and  receives  its  name  from  this  fact. 
Sometimes  this  median  artery  is  very  large,  passes  into 
the  palm,  and  forms  the  superficial  arch  with  the  ulnar. 

The  nutrient  arteries  for  the  radius  and  ulna  are  from  the 
anterior  interosseous  artery,  {p)  The  posterior  interosseous 
passes  directly  backward  between  the  radius  and  ulna,  and 
will  be  found  in  dissecting  the  back  of  the  arm. 

(3)  The  Muscular.  These  are  numerous  and  supply  the 
muscles  near  by. 

(4)  Posterior  carpal.  Is  given  off  just  above  the  wrist- 
joint,  and  turns  backward  under  the  tendon  of  the  flexor 
carpi  ulnaris  to  the  back  of  the  hand. 

(5)  The  anterior  carpal.  A  small  artery  to  the  front 
of  the  carpus  to  supply  this  region  along  with  the  anterior 
carpal  branch  of  the  radial. 

For  the  remaining  branches  in  the  hand  see  page  304. 

The  Ulnar  Nerve.      Fig.  67. 

Is  found  entering  the  forearm  from  behind  the  internal 
condyle  of  the  humerus,  then  passes  betw^een  the  two  heads 
of  the  flexor  carpi  ulnaris,  and  descends  upon  the  flexor 
profundus  digitorum.  It  joins  the  ulnar  artery  at  the  upper 
and  middle  thirds  of  the  forearm,  continues  at  the  ulnar 
side  of  the  artery,  and  with  it  passes  over  the  anterior 
annular  Hgament  at  the  outer  side  of  the  pisiform  bone  into 
the  hand. 

In  the  forearm  the  ulnar  nerve  supplies  filaments  to  the 
flexor  carpi  ulnaris  and  the  inner  portion  of  the  flexor  pro- 
fundus dig-itorum. 


298  A  MANUAL  OF  ANATOMY. 

The  dorsal  cutaneous  branch  of  the  ulnar  nerve  is 
found  about  two  inches  above  the  wrist ;  it  turns  backward 
under  the  tendon  of  the  flexor  carpi  ulnaris  muscle  to  the 
back  of  the  hand,  where  it  will  be  found. 

The  Median  Nerve.       Fig.  dj. 

At  the  elbow  the  median  nerve  lies  at  the  inner  side  of 
the  brachial  artery.  It  descends  between  the  two  heads  of 
the  pronator  radii  teres,  then  directly  down  the  centre  of 
the  forearm  between  the  flexor  sublimis  and  flexor  profun- 
dus digitorum  muscles  to  enter  the  hand  through  the  cen- 
tral compartment  of  the  anterior  annular  ligament  with  the 
tendons  of  the  above  muscles. 

It  supplies  directly  the  pronator  radii  teres,  flexor  carpi 
radialis,  palmaris  longus,  flexor  sublimis  digitorum,  and 
through  the  anterior  interosseous  branch  the  flexor  longus 
polHcis,  the  outer  portion  of  the  flexor  profundus  digitorum^ 
and  the  pronator  quadratus. 

The  Palmar  Cutaneous  branches  of  the  median  and  ulnar 
nerves. 
These  small  nerves  should  be  looked  for  just  above  the 
wrist,  while  removing  the  superficial  fascia  from  the  fore- 
arm ;  the  median  branch  is  in  the  middle  and  the  ulnar 
along  the  inside  of  the  wrist. 

Flexor  Longns  Pollicis.      Fig.  67. 

Origin. — From  the  anterior  surface  of  the  radius  be- 
tween the  oblique  line  above  and  the  pronator  quadratus 
below,  also  (often)  by  a  slender  head  from  the  inner  side  of 
the  coronoid  process  of  the  ulna,  and  from  the  outer  part 
of  the  interosseous  membrane. 

Insertion. — Into  the  palmar  surface  of  the  base  of  the 
last  phalanx  of  the  thumb. 


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30  31    32 

33   34 

Fig.  67.  Dissection  of  Forearm  and  Hand. — i,  The  median  nerve  crossing  the 
brachial  artery.  2,  BrachiaHs  anticus  muscle.  3,  Brachial  artery.  4,  Posterior  interosseous 
nerve.  Its  branching  from  the  musculospiral  is  seen  also.  5,  Radial  recurrent  artery. 
6,  Supinator  brevis  muscle.  7,  Bicipital  tuberosity  of  radius.  8,  Posterior  interosseous 
artery.  9,  Anterior  interosseous  artery.  10,  Radial  nerve,  ii,  Flexor  longus  pollicis.  12, 
Radial  artery.  13,  Superficial  volar  artery.  14,  Tendon  of  the  extensor  ossis  metacarpi 
pollicis  muscle.  15,  Opponens  pollicis.  16,  End  of  the  tendon  of  the  outer  head  of  the  flexor 
brevis  pollicis.  17,  Inner  head  of  the  flexor  brevis  pollicis  (the  adductor  pollicis  obliquus). 
18,  The  adductor  (transversus)  pollicis.  19,  The  deep  transverse  ligament  of  the  fingers.  20, 
The  interossei  muscles.  21,  Opponens  minimi  digiti.  22,  Deep  palmar  arch.  23,  Deep  palmar 
nerve.  24,  Pronator  quadratus.  25,  Flexor  profundus  digitorum.  26,  Anterior  interosseous 
nerve.  27,  Ulnar  artery.  28,  Flexor  carpi  ulnaris.  29,  Ulnar  nerve.  30,  Posterior  ulnar  re- 
current artery.  31,  Anterior  ulnar  recurrent  artery  anastomosing  with  the  anastomotica 
magna.    32,  Internal  condyle.    33,  Anastomotica  magna  artery.    34,  Inferior  profunda  artery. 


300  A  MANUAL   OF  ANATOMY. 

Nei've  Siipply. — From  the  median  by  the  anterior  inter- 
osseous (eighth  cervical  and  first  dorsal  nerves). 
Action. — To  flex  the  thumb,  then  the  wrist. 

Plexor  Profundus  Digitorum.      Fig.  67. 

Origin. — From  the  anterior  and  inner  surfaces  of  the 
ulna  above  the  pronator  quadratus,  from  the  inner  and 
upper  two-thirds  of  the  interosseous  membrane,  from  the 
posterior  ridge  of  the  ulna  in  common  with  the  origin  of 
the  flexor  and  extensor  carpi  ulnaris  muscles. 

Insertion. — Into  the  front  of  the  bases  of  the  last  pha- 
langes of  the  four  fingers. 

Nerve  Snpply. — Ulnar  to  the  inner  portion,  median  (an- 
terior interosseous)  to  the  outer  portion.  The  filaments 
come  from  the  eighth  cervical  and  first  dorsal  nerves. 

Action. — Flexor  of  fingers,  wrist  (all  the  joints  between 
the  lower  end  of  the  radius  and  the  last  set  of  interphalan- 
geal  articulations). 

DISSECTION. 

Incisions. — (i)  Continue  the  median  incision  down  the  palm  and  along 
the  front  of  the  middle  finger.  (2)  Make  a  transverse  cut  across  the  palm 
near  the  web  of  the  fingers.  (3)  Incise  the  skin  down  the  front  of  each 
finger.  (4)  Carry  an  incision  from  the  front  of  the  wrist  along  the  palmar 
surface  of  the  thumb. 

Reflect  the  integument  from  the  palm,  thumb,  and  two  or  more  fingers. 

Be  very  careful  not  to  injure  the  palmar  fascia  and  the  digital  (cutaneous) 
vessels  and  nerves,  which  lie  close  under  the  integument. 

The  palmaris  brevis  muscle,  the  palmar  cutaneous  branches  of  the  median 
and  ulnar  nerves,  the  palmar  fascia,  the  digital  and  collateral  digital  nerves 
and  arteries  are  to  be  carefully  cleaned. 

Palmaris  Brevis.      Fig.  65. 

Origin. — From  the  front  of  the  palmar  fascia  and  an- 
terior annular  ligament. 

Insertion. — Into  the  skin  on  the  ulnar  border  of  the 
palm. 


UPPER  EXTREMITY  AXD   THORAX,  AXTERIOR.       301 

Nen'e  Supply. — Ulnar,  from  first  thoracic  nerve. 

Action. — To  draw  the  skin  toward  the  middle  of  the 
palm. 

The  palmar  cutaneous  nerves  have  already  been  dis- 
sected ;  their  distribution  is  seen  in  removing  the  integu- 
ment. The  ulnar  branch  supplies  the  inner,  the  median 
the  middle  portion  of  the  skin  of  the  palm. 

The  Palmar  Fascia.     Fig.  65. 

This  is  the  deep  fascia  covering  the  muscles  (and  vessels) 
of  the  palm.  The  outer  and  inner  thirds  resemble  the 
deep  fascia  in  other  parts  of  the  body  in  being  thin  and 
forming  a  covering  to  the  muscles.  The  middle  third  is 
so  strengthened  by  additional  transverse  and  vertical  fibres 
that  it  becomes  a  very  dense  fascia.  It  is  narrow  above, 
where  it  is  attached  to  the  annular  ligament  and  receives 
the  fibres  from  the  palmaris  longus  muscle,  spreads  out 
fan-shaped  below,  where  it  divides  into  four  fasciculi  which 
pass  to  the  fibrous  structures  about  the  metacarpopha- 
langeal articulations  and  lateral  margins  of  the  bases  of 
the  first  phalanges  for  their  ultimate  attachments. 

These  fasciculi  are  bound  together  by  cross  fibres  that 
near  the  fingers  exist  as  a  separate  band  and  are  termed 
the  superficial  transverse  lig-ament  of  the  palm.  Between 
these  fasciculi  the  digital  nerves  and  vessels  are  passing  to 
the  fingers,  and  the  lumbrical  and  interossei  muscles  at  a 
deeper  level  to  their  insertions. 

Each  fasciculus  just  over  the  finger  splits  just  before  its 
insertion  to  form  a  passageway  for  the  tendons  of  the  long 
flexor  muscles  to  pass  on  to  the  fingers.  Distally  each 
fasciculus  is  continuous  with  the  digital  sheaths  of  the 
flexor  tendons. 

There  is  another  fasciculus   from  the  outer  side  of  the 


302  A  MANUAL   OF  ANATOMY. 

palmar  fascia  to  the  thumb,  which,  though  thin  and  not  so 
easily  demonstrated  as  the  four  internal  ones,  still  can  be 
shown  to  have  a  similar  arrangement  to  them,  and  to  be 
attached  to  the  ligaments  and  fibrous  structures  about 
the  metacarpophalangeal  articulation.  Between  the  divided 
fasciculus  the  tendon  of  the  long  flexor  passes.  The 
palmaris  brevis  muscle  lies  superficial  to  the  inner  portion 
of  the  inner  or  hypothenar  fascia. 

At  the  extreme  web  of  the  fingers  exists  a  more  or  less 
distinct  band  of  transverse  fibres  (fibres  of  Gerdy),  which 
serve  to  bind  together  the  fingers  and  strengthen  the  hand. 

The  digital  vessels  will  be  found  between  the  fasciculi  of 
the  palmar  fascia,  and  their  position  with  reference  to  the 
bones  of  the  fingers  is  to  be  noted. 


DISSECTION.    . 

Remove  the  lateral  portions  of  the  palmar  fascia,  with  the  inner  the  palmaris 
brevis  muscle,  and  the  central  portion  in  the  follov^ing  way  :  Draw  down- 
ward on  the  tendon  of  the  palmaris  longus  muscle  and  cut  it  and  the  fascia 
carefully  away  from  the  annular  ligament.  \Vhen  the  lower  border  of  the 
annular  ligament  is  passed,  raise  all  of  the  central  portion  of  the  palmar  fascia 
and  separate  it  from  the  vessels  and  nerves  beneath.  When  the  attachments 
of  the  fasciculi  are  reached,  notice  how  they  split  for  the  transmission  of  the 
flexor  tendons,  while  the  lumbricales  and  the  digital  vessels  and  nerves  occupy 
the  space  between  the  fasciculi  themselves.  Then  divide  the  fasciculi  and 
remove  the  fascia  entirely. 

Trace  the  superficial  palmar  arch,  digital  vessels,  and  nerves.  Clean  the 
sheath  of  one  or  more  of  the  long  flexor  tendons  of  the  fingers.  Notice  how 
the  sheath  is  reinforced  by  oblique  and  transverse  cross-bands  of  fibres,  then 
open  it. 

Examine  the  attachments  of  the  anterior  annular  ligament. 

The  muscles  of  the  thumb  and  little  finger  are  to  be  divested  of  their  con- 
nective-tissue covering. 

The  Anterior  Annular  Ligament  of  the  Wrist.     Fig.  66. 

This  is  a  dense  band  of  fibres  reaching  from  the  base  of 

the  thumb  (scaphoid  and  trapezium)  across  the  front  of  the 


UPPER  EXTREMITY  AND   THORAX,  ANTERIOR.       303 

wrist  to  the  base  of  the  Httle  finger  muscles  (pisiform  and 
hook  of  the  unciform).  Above  it  is  continuous  with  the 
deep  layer  of  the  forearm  fascia,  tendon  of  the  palmaris 
longus  muscle,  and  thin  fascia  intervening  between  the 
superficial  and  deeper  layer  of  flexor  muscles  of  the  fore- 
arm. Below  the  palmar  fascia  passes  off  from  its  lower 
border  and  anterior  surface. 

Behind  the  ligament  the  tendons  of  the  long  flexors  of 
the  fingers  and  thumb  and  the  median  nerve  (and  artery  if 
present)  pass  into  the  hand.  Over  the  ligament,  yet  con- 
tained in  compartments  of  the  deep  fascia,  are  found  the 
tendon  of  the  ulnar  flexor,  ulnar  vessels  and  nerve,  the 
tendon  of  the  palmaris  longus  and  radial  flexor  of  the  car- 
pus, then  the  radial  vessels,  and  the  tendons  of  the  extensor 
muscles  of  the  thumb.      This  order  is  from  within  outward. 

Sheaths  of  the  tendons  of  the  long  flexors  of  the 
fingers.  These  are  formed  of  fibrous  tissue  passing  from 
the  sides  of  the  fingers  over  the  front  of  the  tendons.  In 
front  of  the  joints  the  sheaths  are  very  thin,  but  over  the  first 
and  second  phalanges  they  are  reinforced  by  transverse  fibres 
(vaginal  ligaments).  The  sheaths  are  continuous  above 
with  the  lower  margins  of  the  divided  fasciculi  of  the  palmar 
fascia.      Internally  they  are  lined  with  synovial  membrane. 

The  Superficial  Palmar  Arch.     Fig.  66. 

This  arterial  arch  is  formed  by  the  ulnar  artery  curving 
downward  from  the  inside  to  the  outside  of  the  hand,  where 
an  anastomosis  is  established  with  the  radialis  indicis,  prin- 
ceps  poUicis,  superficialis  volae,  separately  ;  or  with  any  two 
or  all  of  them.  It  is  sometimes  formed  by  the  median 
artery,  see  page  297.  The  position  of  the  superficial  arch  is 
indicated  by  a  line  drawn  across  the  palm  on  a  lev'el  with 
the  base  of  the  extended  thumb. 


304 


A  MANUAL   OF  ANATOMY. 


Branches  of  the  Ulnar  in  the  Hand. 

(i)  The  deep  palmar  or  communicating  branch,  is 
given  off  the  posterior  surface  of  the  ulnar,  passes  deeply 
into  the  palm  between  the  abductor  and  flexor  brevis 
minimi  digiti  muscles,  and  ends  by  inosculating  with  the 
radial  to  form  the  deep  arch.      See  page  310. 


Diag.  17. 


(2)  Four  digital  arteries.  These  arise  from  the  lower 
border  of  the  superficial  arch  and  are  distributed  to  the 
fingers.  The  first  crosses  the  muscles  of  the  little  finger  to 
its  inner  side  and  then  runs  along  the  inner  side  of  this 
finger. 

The  second  descends  in  the  interval  between  the  fourth 
and  fifth  metacarpal  bones  to  the  web  of  the  finger,  where 
it  divides  into  two  collateral  digital  arteries,  which  pass  to 


UPPER  EXTREMITY  AND   THORAX,  ANTERIOR.       305 

the  adjacent  sides  of  the  ring  and  little  fingers.  The  third 
takes  a  similar  course  and  distribution  to  the  middle  and 
ring  fingers.  The  fourth  is  distributed  to  the  adjoining  sides 
of  the  index  and  middle  fingers  in  the  same  manner. 

These  digital  arteries  lie  between  the  fasciculi  of  the 
palmar  fascia,  and  long  flexor  tendons  of  the  fingers,  and 
upon  the  lumbrical  muscles  and  digital  nerves,  and  are 
covered  by  the  palmar  fascia. 

Just  before  they  bifurcate  they  are  joined  by  the  inter- 
osseous branches  of  the  deep  arch  and  the  perforating  from 
the  dorsal  interosseous  arteries.  The  remaining  side  of  the 
index  finger  is  supplied  by  the  radialis  indicis,  and  the  thumb 
by  the  princeps  pollicis,  both  from  the  radial  artery.  See 
page  310. 

(3)  The  muscular  and  cutaneous  branches  from  the 
superficial  arch  are  few  and  small. 

The  Digital  Nerves.     Fig.  66. 

The  median  nerve  supplies  two  branches  to  the  thumb, 
one  on  either  side  ;  a  third  to  the  outer  side  of  the  index 
finger  ;  a  fourth,  to  between  the  index  and  middle  ;  and  a 
fifth,  between  middle  and  ring  fingers  ;  each  of  which  sub- 
divide to  supply  the  contiguous  sides  of  these  fingers. 

The  third  and  fourth  nerves  send  a  fine  branch  to  the 
two  outer  lumbrical  muscles,  the  fifth  receives  a  communi- 
cating branch  from  the  ulnar  nerve.  From  the  ulnar  nerve 
the  rest  of  the  fingers  are  supplied,  the  first  digital  branch 
being  given  off  to  the  inner  side  of  the  little  finger,  and  the 
second  to  between  the  little  and  ring  fingers,  which  then 
divides  into  collateral  branches  to  the  adjacent  surfaces  of 
these  two  fingers.  From  the  outer  side  of  the  second 
branch  is  given  a  small  filament  to  join  the  median.  See 
above.  From  the  median  nerve  just  below  the  annular 
20 


306  A  MANUAL  OF  ANA  TO  MY. 

ligament  will  be  found  the  muscular  branches  to  the  thumb 
muscles.  From  the  ulnar  there  passes  into  the  palm  with 
the  deep  communicating  artery  the  deep  palmar  branch  of 
the  ulnar  nerve.  It  also  sends  branches  to  the  palmaris 
brevis  and  little  finger  muscles. 

Superficial  Layer  of  Palmar  Muscles. 

Abductor  Pollicis.      Fisf.  66. 

Origin. — From  the  tuberosity  of  scaphoid,  ridge  of  trape- 
zium, and  fibres  of  palmar  fascia,  annular  ligament,  and 
tendon  of  the  extensor  ossis  metacarpi  pollicis. 

Insertion. — Into  the  anterior  side  of  the  base  of  the  first 
phalanx  of  the  thumb  and  the  aponeurosis  of  the  extensor 
longus  pollicis. 

Nerve  Supply. — Median.  (Filaments  from  the  sixth  cer- 
vical nerve.) 

Action. — To  abduct,  flex  thumb,  and  (through  its  attach- 
ment to  the  thumb  extensor)  it  will  slightly  extend  the  last 
phalanx  of  the  thumb.  (See  action  of  lumbricales  and 
interossei.) 

Outer  Head  of  the  Plexor  Brevis  Pollicis.  (For  the 
inner  see  page  308.)     Fig.  66. 

Origin. — From  the  annular  ligament  and  ridge  of  trape- 
zium. 

Insertion. — The  outer  side  of  the  base  of  the  first  phalanx 
of  the  thumb. 

Nerve  Supply. — From  the  median  (filaments  from  the 
sixth  cervical). 

Action. — Flexion  of  the  carpometacarpal  and  metacar- 
pophalangeal articulations  of  the  thumb.  Acts  with  ab- 
ductor pollicis.    For  deeper  muscles  of  thumb  see  page  308. 

Abductor  Minimi  Dig-iti.     Fig.  66. 
Origin. — From  the  pisiform  bone. 


UPPER  EXTREMITY  AND  THORAX,  ANTERIOR.       307 

Insertion. — The  inner  side  of  the  base  of  the  first  phalanx 
of  the  little  finger,  and  by  an  extension  to  the  extensor 
tendon  behind. 

Nerve  Supply. — The  ulnar,  by  filaments  from  the  eighth 
cervical. 

Action. — Abduction  and  flexion  of  the  metacarpophalan- 
geal joint,  with  extension  of  the  last  two  phalanges  of  the 
little  finger.      (See  action  of  lumbricales  and  interossei.) 

Flexor  Brevis  Minimi  Digiti.     Fig.  66. 

Origin. — From  the  annular  ligament  and  hook  of  the 
unciform  bone. 

Insertion. — Into  the  inner  side  of  the  base  of  the  first 
phalanx  of  the  little  finger. 

Nen>e  Supply. — Ulnar.      Same  as  for  the  abductor. 

Action. — Flexor  of  first  joint  of  little  finger. 

Note. — Between  the  abductor  and  flexor  muscles  pass  the  deep  palmar 
communicating  artery  and  nerve. 

The  Lumbricales. 

Four  in  number. 

Origin. — Begin  at  the  lower  border  of  the  annular  liga- 
ment from  the  anterior  surface  and  radial  border  of  all  the 
tendons  of  the  flexor  profundus  digitorum.  In  addition, 
the  two  inner  muscles  are  attached  to  the  ulnar  sides  of 
the  adjacent  tendons. 

Insertion. — Into  the  radial  sides  of  the  aponeurosis  of  the 
extensor  communis  digitorum  muscle  opposite  the  first 
phalanx. 

Nei'\>e  Supply. — The  two  outer  by  the  median  the  two 
inner  from  the  deep  branch  of  the  ulnar. 

Action. — Flexion,  abduction  (from  median  line  of  the 
body)  of  the  first  set  of  phalanges  of  the  fingers  ;  extension 


308  A  MANUAL   OF  ANA  TOMY. 

of  the  last  two  sets  of  phalanges  through  their  connections 
with  the  common  extensor  aponeurosis. 

DISSECTION. 

Divide  the  abductor  pollicis  and  reflect  its  portions ;  cut  through  the  annu- 
lar ligament,  note  the  relations  of  the  tendons  of  the  long  flexor  muscles  and 
the  median  nerve,  also  the  extension  up  under  the  ligament  of  the  synovial 
sac  of  these  tendons. 

Divide  the  ulnar  artery  and  nerve  just  below  their  deep  palmar  branches; 
sever  the  connections  of  the  superficial  arch  at  the  base  of  the  thumb  and  turn 
the  digital  nerves  and  arteries  and  the  tendons  of  the  sublimis  and  profundus 
digitorum,  with  the  lumbricales,  below  the  web  of  the  fingers. 

Clean  the  rest  of  the  thumb  and  little- finger  muscles,  the  deep  palmar  arch 
and  its  branches. 

The  Inner  Head  of  the  Plexor  Brevis  Pollicis.  {Adduc- 
tor Obligims.)     Fig.  67. 

Origm. — From  the  sheath  of  radial  flexor  of  carpus,  os 
magnum,  and  bases  of  second  and  third  metacarpal  bones. 

Insertion. — Into  the  inner  side  of  the  base  of  the  first 
phalanx  of  the  thumb  with  the  adductor  pollicis  ;  and  by  a 
separate  fasciculus  into  the  outer  side  of  the  base  of  the 
same  bone  with  the  outer  head  of  the  flexor  brevis  pollicis. 

Nerve  Supply. — By  the  deep  branch  of  the  ulnar  from 
the  eighth  cervical  nerve. 

Action. — To  adduct  and  flex  the  carpometacarpal  and 
metacarpophalangeal  articulations  acting  with  the  adductor 
pollicis  muscle. 

Adductor  Pollicis.     {Adductor  Transversals^     Fig.  6j. 

Origin. — From  the  lower  two-thirds  of  the  front  of  the 
third  metacarpal  bone. 

Insertion. — Into  the  inner  side  of  the  base  of  the  first 
phalanx  of  the  thumb,  with  the  inner  head  of  the  flexor 
brevis  muscle,  and  into  the  inner  portion  of  the  aponeurosis 
of  the  extensor  longus  pollicis. 


UPPER  EXTREMITY  AND  THORAX,  ANTERIOR.       309 

Nerve  Supply. — The  ulnar,  through  the  deep  branch  ;  the 
filaments  coming  from  the  eighth  cervical  nerve. 

Action. — To  adduct  and  flex  the  carpometacarpal  joint, 
to  flex  this  and  the  metacarpophalangeal  joints.  By  its 
attachment  to  the  extensor  aponeurosis  it  will  extend  the 
last  phalanx  of  the  thumb. 

Opponens  Pollicis.      Fig.  dy . 

Origin. — From  the  annular  ligament  and  the  ridge  of  the 
trapezium. 

Insertion. — Into  the  front  of  the  metacarpal  bone  of  the 
thumb. 

Nerve  Supply. — The  median  from  the  sixth  cervical  nerve. 

Action. — To  flex  and  adduct  the  metacarpal  bone  of  the 
thumb. 

Opponens  Minimi  Dig-iti.     Fig.  67. 

Origin. — From  the  annular  ligament  and  the  hook  of  the 
unciform  bone. 

Insertion. — Into  the  entire  length  of  the  inner  border  of 
the  fifth  metacarpal  bone. 

Nerve  Supply. — The  ulnar  nerve  from  the  eighth  cervical. 

Action. — Flexion  and  adduction  (slight)  of  the  fifth  meta- 
carpal bone. 

Palmar  Interossei.      (Three.) 

Origin. — From  the  side  of  the  metacarpal  bones  of  the 
index,  ring-,  and  little  fingers.  The  first  arises  from  the 
inner,  the  second  and  third  from  the  outer  side  of  the  re- 
spective metacarpal  bones. 

Insertion. — Into  the  base  of  the  first  phalanges  of  the 
corresponding  fingers,  and  by  an  extension  into  the  apon- 
eurosis of  the  extensor  tendons.  The  first  being  inserted 
on  the  inner,  the  second  and  third  into  the  outer  sides  of 
their  respective  fingers. 


310  A  MANUAL  OF  ANA  TOMY. 

Nerve  Supply. — From  the  ulnar,  by  its  deep  palmar 
branch.  The  filaments  arising  from  the  eighth  cervical 
nerve. 

Action. — See  Dorsal  interossei. 

The  Deep  Palmar  Arch.     Diag.  1 8.     Fig.  ^y. 

After  the  radial  artery  has  gained  the  front  of  the  hand 
by  coming  through  between  the  first  and  second  metacar- 
pal bones,  it  turns  inward  between  the  adductor  and  inner 
head  of  the  flexor  brevis  pollicis,  and  crosses  the  bases  of 
the  second,  third,  and  fourth  metacarpal  bones  and  inter- 
ossei muscles,  to  form  the  deep  arch  by  anastomosing  with 
the  deep  communicating  artery  from  the  ulnar. 

The  line  indicating  the  deep  arch  is  half  an  inch  nearer 
the  wrist-joint  than  the  superficial. 

Branches  of  the  Deep  Arch.     (Radial  in  the  hand.) 

(a)  Princeps  pollicis,  is  a  branch  from  the  radial  just 
as  it  enters  the  palm.  It  passes  outward  and  downward 
between  the  adductor  pollicis  and  the  abductor  indicis 
muscles.  Over  the  metacarpophalangeal  joint  it  divides 
into  two  branches,  one  for  each  side  of  the  thumb,  (p) 
Radialis  indicis,  issues  between  the  adductor  pollicis  and 
abductor  indicis  muscles,  descends  along  the  outer  anterior 
border  of  the  index  finger  to  its  tip.  (c)  Palmar  interos- 
seous arteries,  three  in  number ;  descend  between  the  in- 
dex and  middle,  middle  and  ring,  and  ring  and  little  fingers, 
along  the  anterior  surface  of  the  interossei  muscles,  and 
terminate  by  joining  the  digital  branches  from  the  super- 
ficial arch.  See  page  305.  They  supply  the  adjoining 
muscles,  (d)  The  recurrent,  are  two  or  more  small  twigs 
which  pass  upward  to  the  front  of  the  carpus  and  form  an 
anastomosis  with  the  anterior  carpal  branches  of  the  radial, 
ulnar,  and  anterior  interosseous  arteries.     (/)  The  perforat- 


UPPER  EXTREMITY  AND  THORAX,  ANTERIOR.       311 

ing,  also  usually  three  in  number,  pass  to  the  back  of  the 
hand  through  the  second,  third,  and  fourth  interosseous 
spaces,  to  end  in  the  dorsal  anastomoses. 

The  Tendons  of  the  Long  Plexor  Muscles  of  the  Fin- 
gers. 

After  opening  the  sheath  of  one  or  two  fingers  and  hav- 
ing seen  its  formation,  notice  how  the  long  flexor  tendons 
are  attached  to  the  phalanges.  It  will  be  seen  that  the 
flexor  sublimis  tendon  lies  anterior  to  the  profundus  until 
the  middle  of  the  first  phalanx  is  reached,  where  it  divides 
into  two  parts,  which  pass  around  and  reunite  behind  the 
deep  tendon,  over  the  base  of  the  second  phalanx.  The 
tendons  again  divide  and  pass  to  their  insertion  into  the 
sides  of  the  second  phalanx. 

The  tendons  within  their  sheaths  are  surrounded  by  syn- 
ovial membrane.  These  synovial  sacs  reach  from  the  in- 
sertion of  the  long  flexor  tendons  to  the  heads  of  the 
metacarpal  bones.  The  synovial  sheaths  for  the  index, 
middle,  and  ring  fingers  are  distinct  from  the  great  palmar 
synovial  membrane.  That  for  the  little  finger  reaches  up 
to  it  and  may  connect  with  it.      See  Diag.  i8. 

The  great  palmar  synovial  membrane  envelopes  the 
tendons  of  the  flexor  sublimis  and  profundus  digitorum 
from  the  middle  of  the  palm  to  an  inch  above  the  annular 
ligament  of  the  wrist.  This  is  distinct  from  the  synovial 
membranes  for  the  fingers,  excepting  that  the  sheath  for 
the  little  finger  may  open  into  it. 

The  flexor  longus  pollicis  is  surrounded  by  a  similar 
synovial  sheath  that  reaches  from  the  insertion  of  the 
tendon  to  a  like  distance  above  the  annular  ligament. 
This  sac  lies  in  contact  with,  and  often  communicates  with, 
the  above  sheath  for  the  flexors  of  the  finders. 


312 


MANUAL   OF  ANATOMY. 


Hence  a  suppuration  starting  in  the  little  finger  may- 
point  in  the  region  of  the  thumb  or  extend  above  the 
wrist.  Inflammations  of  the  sheaths  of  the  index,  middle, 
and  ring  fingers  are  limited  to  those  fingers  and  do  not  as 
a  rule  spread  into  the  palm. 

The  foregoing  completes  the  dissection  of  the  anterior 
part  of  the  upper  extremity,  excepting  the  study  of  the 
formation  of  the  brachial  plexus,  which  was  purposely 
omitted  until  the  neck  had  been  dissected.      Now,  working 


Diag.  i8. 


with  the  one  dissecting  the  neck,  disarticulate  the  clavicle 
at  its  sternal  end  (having  previously  studied  the  ligaments 
of  this  joint),  divide  the  subclavius  muscle  near  its  costal 
attachment,  and  carry  the  clavicle  outward.  This  will  give 
sufficient  room  without  entirely  removing  the  clavicle. 
For  the  third  portion  of  the  Subclavian  Artery  see  page  109. 

The  Brachial  Plexus.       Figs.  63,  64. 

The  brachial  plexus  is  formed  by  the  anterior  branches 
of  the  fifth,  sixth,  seventh,  and  eighth  cervical  and  the  first 


313 


314  A  MANUAL   OF  ANATOMY. 

dorsal  nerve,  with  branches  from  the  fourth  cervical  and  the 
second  dorsal  nerves. 

The  cervical  nerves  emerge  along  the  side  of  the  neck 
between  the  anterior  and  middle  scaleni  muscles.  The 
first  dorsal  passes  over  the  upper  border  of  the  first  rib  to 
join  the  last  cervical  nerve. 

The  plexus  is  conveniently  divided  into  stages  for  de- 
scription : — 

(i)  The  nerve  roots.  (2)  The  junction  of  the  nerves  to 
form  trunks,  the  fifth  and  sixth  nerves  forming  the  upper, 
the  seventh  the  middle,  and  the  eighth  and  first  dorsal  the 
lower  trunks.  (3)  The  division  of  these  trunks  into 
anterior  and  posterior  branches.  The  division  is  about 
equal  in  the  upper  and  middle  trunk,  but  in  the  lower  the 
anterior  division  is  much  larger  than  the  posterior.  (4) 
The  union  of  these  divisions  to  form  cords.  The  anterior 
divisions  of  the  upper  and  middle  trunks  forming  the  outer 
cord.  The  anterior  division  of  the  lower  trunk  continuing 
as  the  inner  cord,  and  the  junction  of  the  posterior 
divisions  of  all  three  trunks  forming  the  posterior  cord. 
The  first  and  second  portions  of  the  plexus  lie  in  the  neck 
above  and  to  the  outside  of  the  subclavian  artery.  The 
third  portion  is  behind  the  clavicle  and  the  subclavius 
muscle  and  at  the  outside  of  the  axillary  artery.  The 
fourth  portion  surrounds  the  axillary  artery,  the  outer 
cord  being  to  the  outside,  the  inner  cord  to  the  inside,  and 
the  posterior  cord  behind,  the  axillary  artery. 

Branches  of  the  Plexus. 

(i)  From  the  first  portion  of  the  plexus. 

(«)  From  the  fifth  nerve,  the  rhomboid  branch.  (/;)  The 
communicating  to  the  phrenic,  (r)  The  first  part  of  the 
posterior  or  long  thoracic.  {cT)  From  the  sixth  and  the 
seventh,  branches  to  the  scaleni,  longus  colli   muscles,  and 


UPPER  EXTREMITY  AND  THORAX,  ANTERIOR.       315 

to  the  posterior  thoracic  nerve.  {/)  The  posterior  or  long- 
thoracic  nerve  is  formed  in  the  substance  of  the  scalenus 
medius  by  branches  from  the  fifth,  sixth,  and  seventh  cer- 
vical nerves.  It  passes  downward  behind  the  plexus  and 
the  beginning  of  the  axillary  artery  into  the  axillary  space, 
where  it  is  found  coursing  along  the  middle  of  the  serratus 
magnus  muscle,  to  which  it  is  distributed. 

(2)  From  the  second  portion  of  the  plexus,  (c?)  Nerve 
to  the  subclavius.  This  small  nerve  comes  from  the  upper 
trunk  just  after  its  formation,  descends  across  the  brachial 
plexus  and  subclavian  vessels  to  supply  the  subclavius 
muscle.  {b^  Suprascapular  nerve.  This  arises  from 
the  upper  trunk,  passes  outward  and  downward  through 
the  suprascapular  foramen  in  the  scapula  (notch  con- 
verted into  a  foramen  by  the  transverse  ligament),  supplies 
the  supraspinatus  muscle,  the  shoulder-joint,  continues 
around  through  the  great  scapular  notch,  and  termi- 
nates in  the  infraspinatus  muscle.  All  the  preceding  nerves 
arise  from  the  plexus  above  the  clavicle. 

(3)  From  the  fourth  portion  of  the  plexus.  Below  the 
clavicle.  From  the  outer  cord,  {a)  The  external  anterior 
thoracic  nerve  receives  filaments  from  the  fifth,  sixth,  and 
seventh  cervical  nerves,  arises  from  the  outer  cord,  turns 
inward  across  the  axillary  artery  and  vein,  perforates  the 
costocoracoid  membrane,  and  supplies  the  pectoralis  major. 
iU)  The  musculocutaneous  nerve.  This  nerve  is  the 
direct  continuation  of  the  outer  cord.  It  continues  to 
the  outer  side  of  the  third  portion  of  the  axillary  artery 
and  the  beginning  of  the  brachial,  perforates  the  coraco- 
brachialis  muscle  (supplying  it),  descends  between  the 
biceps  and  brachialis  anticus  (supplying  both),  and  as  a 
cutaneous  nerve  is  distributed  to  the  outer  portion  of  the 


316  A  MANUAL   OF  ANATOMY. 

anterior  surface  of  the  forearm  as  low  as  the  ball  of  the 
thumb.      (<r)  The  outer  head  of  the  median. 

From  the  inner  cord,  {a)  The  internal  anterior  tho- 
racic. It  passes  upward  between  the  axillary  artery  and 
vein  from  the  inner  cord  to  the  under  surface  of  the  pecto- 
ralis  minor  muscle.  Some  filaments  pass  through  the 
minor  and  terminate  in  the  major.  The  external  and  inter- 
nal nerves  form  a  slight  interlacement  with  each  other 
between  the  two  pectoral  muscles.  [6)  The  lesser  internal 
cutaneous  descends  to  the  floor  of  the  axillary  space 
and  enters  into  a  loose  plexus  with  the  intercosto- 
humeral  nerve.  The  nerve  itself  is  distributed  to  the 
skin  of  the  inner  and  back  part  of  the  arm  over  and 
above  the  olecranon  process,  {c)  The  internal  cutaneous 
nerve,  another  branch  from  the  internal  cord,  passes  through 
the  axillary  space,  along  the  inner  side  of  the  arm  above 
the  elbow,  divides  into  two  branches,  the  anterior,  which 
supplies  the  skin  of  the  inner  half  of  the  front  of  the  fore- 
arm as  low  as  the  wrist,  and  the  posterior  branch,  which 
takes  a  similar  supply  upon  the  back  of  the  inside  of  the 
forearm,  {d^  The  ulnar  nerve.  This  continues  the  direct 
course  of  the  inner  cord,  descends  along  the  inside  of  the 
arm  with  the  inferior  profunda  artery,  behind  the  internal 
condyle  of  the  humerus  with  the  recurrent  branch  of  the 
ulnar,  between  the  two  heads  of  the  flexor  carpi  ulnaris 
muscle,  then  between  the  flexor  sublimis  and  profundus 
digitorum  muscles  ;  at  the  middle  and  upper  thirds  of  the 
forearm  joins  the  ulnar  artery  at  its  inner  side,  keeps  this 
position  with  reference  to  the  artery  into  the  hand  ;  here  it 
divides  into  its  terminal  digital  branches. 

Branches  of  the  Ulnar  Nerve. — In  the  arm  (behind  the 
condyle)    articular  to    the   elbow-joint.      In   the    forearm, 


UPPER  EXTREMITY  AND  THORAX,  ANTERIOR.       317 

muscular  to  the  flexor  carpi  ulnaris  and  flexor  profundus 
digitorum  (inner  portion).  In  the  hand,  digital  to  the 
inner  side  of  the  little  finger,  the  adjacent  sides  of  the  little 
and  ring  fingers  ;  communicating  to  the  inner  digital  branch 
of  the  median  ;  muscular  to  the  palmaris  brevis,  flexor, 
abductor,  and  opponens  minimi  digiti,  to  the  two  inner 
lumbricals,  all  the  interossei,  the  adductor  and  inner  head  of 
the  flexor  brevis  pollicis  (adductor  obliquus).  (r)  The  inner 
head  of  the  median. 

The  median  nerve.  The  median  nerve  is  formed  at  the 
outer  side  of  the  third  portion  of  the  axillary  artery  by  a 
branch  from  the  outer  and  inner  cords,  the  branch  from  the 
inner  cord  crossing  in  front  of  the  artery  to  get  to  its 
outer  side.  The  nerve  then  continues  down  the  front  of 
the  arm  in  the  same  sheath  with  the  brachial  artery,  cross- 
ing either  in  front  or  behind  the  artery  to  attain  its  inner 
side  at  the  elbow.  From  the  elbow  the  nerve  descends 
through  the  forearm,  passing  between  the  two  heads  of  the 
pronator  radii  teres,  then  between  the  flexor  sublimis  and 
the  flexor  profundus  digitorum  muscles.  At  the  wrist  the 
median  traverses  the  central  compartment  of  the  annular 
ligament  and  enters  the  palm,  where  it  breaks  up  into  its 
terminal  branches.  At  the  elbow,  the  median  gives  off  an 
articular  branch  to  the  joint  and  muscular  to  the  super- 
ficial layer  of  muscles  ;  these  muscles  are  the  pronator  radii 
teres,  flexor  carpi  radialis,  palmaris  longus,  and  flexor 
sublimis  digitorum  ;  then  through  its  anterior  interosseous 
branch  it  supplies  the  flexor  longus  pollicis,  the  outer  side  of 
the  flexor  profundus  digitorum,  and  the  pronator  quadratus. 
In  the  hand,  the  median  supplies  the  abductor,  opponens, 
and  outer  head  of  the  flexor  brevis  pollicis  muscles,  and  the 
outer  two  lumbricals.  The  digital  distribution  is  to  the 
thumb,  the  index,  middle,  and  outer  side  of  the  ring  fingers. 


318  A  MANUAL   OF  ANA  TOMY. 

The  digital  branch  to  the  ring  finger  receives  a  communi- 
cating branch  from  the  ulnar.      See  Ulnar  above. 

From  the  posterior  cord,  {a)  The  subscapular  nerves, 
three  in  number,  arise  from  the  posterior  cord  immediately 
after  its  formation.  The  first  (upper)  supplies  the  upper 
part  of  the  subscapularis  muscle.  The  second  (the  long) 
the  latissimus  dorsi  muscle.  The  third  (lower)  the  lower 
portion  of  the  subscapularis  and  the  teres  major  muscles. 
{h)  The  circumflex  nerve.  Turns  backward  with  the 
posterior  circumflex  artery  through  the  quadrilateral  space 
formed  by  the  humerus,  long  head  of  triceps,  subscapularis 
(teres  minor  behind),  and  teres  major  muscles,  to  be  dis- 
tributed to  the  teres  minor  and  deltoid  muscles  and  the 
integument  over  the  outer  and  posterior  part  of  the 
shoulder,  {c)  The  Musculospiral.  Continues  the  pos- 
terior cord  into  the  arm.  It  winds  through  the  groove  of 
the  same  name  with  the  superior  profunda  artery  to  reach 
the  interval  at  the  outer  side  of  the  elbow  between  the 
supinator  longus  (brachioradialis)  and  the  brachialis  anti- 
cus,  where  it  divides  into  its  two  terminal  branches,  the 
radial  and  posterior  interosseous.  The  radial  descends 
under  cover  of  the  supinator  longus  to  the  lower  third  of 
the  wrist,  turns  backward  to  the  posterior  part  of  the  hand, 
and  supplies  the  integument  on  the  back  of  the  hand  and 
two  and  one-half  fingers  (thumb,  index,  and  outer  side  of 
the  middle  fingers).  The  posterior  interosseous  passes 
backward  through  the  supinator  brevis,  and  descends  be- 
tween the  posterior  muscles  of  the  forearm  as  low  as  the 
back  of  the  carpus,  where  it  terminates  in  a  gangliform  en- 
largement. The  musculospiral  supplies  the  triceps,  supi- 
nator longus,  extensor  carpi  radialis  longior,  and  anconeus 
muscles ;  and  by  its  superior  and  inferior  cutaneous 
nerves  the  integument  of  the  lower  part  of  the  outer  side  of 


THE  THORAX.  319 

the  arm,  and  the  posterior,  outer  surface  of  the  forearm 
nearly  to  the  elbow.  The  posterior  interosseous  nerve  sup- 
plies the  extensor  carpi  radialis  brevior,  supinator  brevis, 
extensor  communis  digitorum,  extensor  minimi  digiti,  ex- 
tensor carpi  ulnaris,  extensor  metacarpi  pollicis,  extensor 
indicis,  extensor  brevis,  and  longus  pollicis  muscles.  The 
intercostohumeral  nerve,  after  entering  into  a  plexi- 
form  arrangement  with  the  lesser  internal  cutaneous  and 
cutaneous  branch  of  the  third  intercostal  nerve  at  the  floor 
of  the  axilla,  continues  outward,  downward,  and  sends  some 
filaments  posteriorly  to  supply  the  integument  of  the  upper 
posterior  part  of  the  arm  and  axilla,  over  the  latissimus 
dorsi  muscle. 

The  nerves  receive  their  filaments  from  the  following 
sources  : — 

The  suprascapular  and  subclavius — 5,  6,  7.  * 

The  external  anterior  thoracic,  5,  6,  7. 

Musculocutaneous,  5,  6,  7. 

The  internal  anterior  thoracic,  8,  i. 

Lesser  internal  cutaneous  and  internal  cutaneous,  8,  i. 

Ulnar,  (7),  8,  i. 

Subscapular,  circumflex,  and  musculospiral,  5,  6,  7,  8. 

The  median,  5,  6,  7,  8,  i. 

THE  THORAX. 

For  the  landmarks  see  page  255. 

The  dissection  of  the  soft  parts  anterior  to  the  ribs  has  been  already  per- 
formed, and  their  description  given  in  the  preceding  pages. 

Remove  the  sternum  and  costal  cartilages  by  cutting  through  the  latter  as 
close  to  the  ribs  as  possible  (when  the  ribs  are  not  needed,  the  division  had 

*  Numerals  refer  to  the  number  of  the  cervical  and  dorsal  nerves  forming 
the  brachial  plexus. 


320  A  MANUAL   OF  ANATOMY. 

better  be  made  through  them  along  the  anterior  axillary  line,  using  a  small 
saw  or  bone  cutters  for  the  purpose)  until  the  seventh  rib  is  reached ;  cut  the 
muscles  between  it  and  the  sixth  up  to  the  sternum,  and  saw  through  the 
latter  just  above  the  point  where  the  seventh  costal  cartilage  articulates  with 
it. 

Beginning  above,  raise  the  sternum,  dividing  the  internal  mammary  arteries 
as  close  to  it  as  possible,  and  remove  the  sternum  and  cartilages  (and  portions 
of  ribs  if  they  have  been  sawn  through)  from  the  thoracic  contents  by  careful 
dissection,  so  as  not  to  injure  them. 

On  the   Sternum. 

Triangularis  Sterni.      (Continuation  upward  of  the  trans- 
versalis.) 

Origin. — From  the  internal  surface  of  the  fifth,  sixth,  and 
seventh  costal  cartilages,  the  ensiform  appendix,  and  the 
lateral  margins  of  sternum  for  its  lower  third. 

Insertion. — Into  the  inner  surface  and  lower  border  of 
the  second  to  the  sixth  cartilages,  close  to  their  costal 
junction. 

Nerve  Supply. — The  upper  intercostals. 

Action. — Feeble  muscle  of  expiration,  by  depressing  the 
inner  anterior  portions  of  the  ribs  to  which  it  is  attached. 

DISSECTION. 
Remove  the  above  muscle.     Trace  the  internal  mammary  artery  and  its  an- 
terior and  lateral  branches  as  far  as  possible. 

The  Internal  Mammary  Artery.      Figs.  i8,  68. 

Arises  from  the  under  surface  of  the  first  portion  of  the 
subclavian  artery,  close  to  the  inner  border  of  the  scalenus 
anticus  muscle,  and  opposite  the  thyroid  axis.  See  page 
113.  It  passes  into  the  chest  and  descends  behind  the 
cartilages  of  the  ribs  about  half  an  inch  from  the  external 
margin  of  the  sternum  until  the  sixth  space  is  reached, 
where  it  divides  into  the  superior  epigastric  and  the  muscu- 
lophrenic. 


THE   THORAX.  321 

The  superior  epigastric  continues  downward,  enters  the 
under  surface  of  the  rectus  muscle  (piercing  its  sheath),  and 
finally  terminates  in  anastomotic  branches  with  the  deep 
epigastric. 

The  musculophrenic  passes  downward  and  outward 
across  the  costal  cartilages  of  the  false  ribs  and  along  the 
origin  of  the  diaphragm,  which  it  perforates  over  the  ninth 
rib,  to  the  tenth  or  eleventh  intercostal  space.  In  its  course 
it  supplies  the  intercostal  muscles  and  the  diaphragm. 

Relations. — In  the  neck,  the  internal  mammary  is  crossed 
in  front  by  the  phrenic  nerve,  which  passes  from  the  outside 
to  the  inner  side  of  the  artery,  and  by  the  subclavian  vein. 
The  artery  in  the  upper  part  of  its  course  is  in  contact  with 
the  pleura,  but  in  the  lower  is  separated  from  it  by  the  tri- 
angularis sterni  muscle. 

Brandies. — A  small  artery  to  accompany  the  phrenic 
ner\^e,  given  off  at  the  upper  opening  of  the  thorax. 

The  anterior  intercostal  arteries  are  a  pair  in  each  of  the 
upper  six  intercostal  spaces.  These  turn  outward  to  anas- 
tomose with  the  aortic  intercostals,  supplying  the  surround- 
ing parts. 

The  perforating.  One  for  each  of  the  six  upper  spaces. 
Pass  forward  and  are  distributed  to  the  parts  upon  the  front 
of  the  chest.  The  mammary  gland  receives  blood  from  the 
second,  third,  and  fourth. 

Besides  these  there  are  small  branches  to  the  mediasti- 
num, sternum,  and  pericardium. 

The  internal  mammary  artery  is  accompanied  by  two 
veins  which  empty  into  the  innominate  vein  of  that  side. 

Parts  Within  the  Thorax. — If  the  pleurae  have  been  saved 
uninjured  in  removing  the  sternum  and  cartilages  (and  ribs), 
they  will  be  seen  to  form  a  closed  sac  within  which  the 
lungs  are  contained.      By  inflating  the  lungs  they  will  ex- 

21 


322  A  MANUAL  OF  ANA  TOMY. 

pand  and  fill  up  the  chest,  their  anterior  borders  will  come 
into  contact.  The  heart  will  be  seen  to  be  contained  in  a 
similar  membranous  sac,  the  pericardium,  though  it  is  much 
stronger  than  the  pleurae. 

The  space  between  the  lungs  (and  pleurae),  sternum,  and 
spine,  and  reaching  from  the  root  of  the  neck  to  the 
diaphragm,  is  the  mediastinum. 

The  Mediastinum,     Figs.  68  to  72. 

The  mediastinal  space  is  the  central  portion  of  the 
thoracic  cavity  between  the  pleural  sacs  laterally,  the  ster- 
num and  cartilages  in  front,  the  vertebral  column  behind, 
the  diaphragm  below,  and  the  superior  aperture  of  the 
thorax  above. 

The  mediastinum  is  divided  into  several  portions,  as  the 
superior,  anterior,  middle,  and  posterior. 

The  superior  mediastinum  lies  behind  the  first  piece  of 
the  sternum.  In  front  are  the  sternal  origins  of  the  sterno- 
hyoid and  sternothyroid  muscles  ;  behind,  are  the  four 
upper  dorsal  vertebrae  and  the  longus  colli  muscle.  It 
contains  the  trachea,  oesophagus,  and  thoracic  duct ;  trans- 
verse aorta,  innominate  artery,  the  thoracic  portions  of  the 
left  carotid  (common),  and  subclavian  arteries  ;  the  innomi- 
nate veins,  the  upper  portion  of  the  superior  vena  cava  ;  the 
pneumogastric,  left  recurrent  laryngeal,  the  phrenic,  sym- 
pathetic, and  cardiac  nerves  ;  lymphatic  and  thymus  glands  ; 
longus  colli,  sternohyoid,  and  sternothyroid  muscles. 

The  anterior  mediastinum  is  all  that  portion  of  the 
mediastinum  anterior  to  the  pericardium.  It  corresponds 
to  the  area  of  heart  dullness.  It  contains  a  little  areolar 
tissue  and  a  few  small  lymphatic  glands. 

The  middle  mediastinum  is  the  central  portion  of  the 
space.      It  contains  the  heart,  ascending  aorta,  pulmonary 


THE  THORAX.  323 

artery,  and  lower  portion  of  the  superior  vena  cava  (all 
within  the  pericardium) ;  the  phrenic  nerves  and  their 
accompanying  arteries  ;  the  azygos  vein  (termination)  ;  the 
roots  of  the  lungs  and  some  bronchial  lymphatic  glands. 

The  posterior  mediastinum  is  that  portion  of  the  space 
between  the  pleurse  laterally,  the  pericardium  and  roots  of 
the  lungs  in  front,  and  the  spine  (below  the  fourth  dorsal 
vertebra)  behind. 

It  contains  the  descending  and  thoracic  aorta,  the  oeso- 
phagus, pneumogastric  nerves,  azygos  veins,  thoracic  duct, 
and  lymphatic  glands,  sympathetic  cord,  ganglia,  and 
splanchnic  nerves. 

Structures  which  traverse  the  superior  opening  of  the 
chest : — 

Muscles. — Sternohyoid,  sternothyroid,  longus  colli. 

Arteries. — Innominate,  left  common  carotid,  left  subcla- 
vian, internal  mammary,  superior  intercostal. 

Veins. — Left  innominate,  right  internal  jugular  and  sub- 
clavian, inferior  thyroids,  and  superior  intercostals. 

Nerves. — Phrenics,  pneumogastrics,  cardiac,  sympathetic 
cord,  recurrent  laryngeal. 

Other  Structures. — Thymus  gland,  thoracic  duct,  trachea, 
oesophagus,  apices  of  lungs,  pleurae,  cervical  fascia. 

DISSECTION. 

If  the  pleurje  have  been  preserved  whole,  remove  the  presenting  portion. 
Trace  the  phrenic  nerves  and  save  the  arterial  branch  (very  small)  that  accom- 
panies them. 

Carefully  dissect  away  the  areolar  tissue  in  the  superior  and  anterior  medi- 
astina,  exposing  the  remains  of  the  thymus  gland,  the  great  vessels,  and 
pericardium. 

The  Pleurae. 

Each  pleura  is  a  closed  sack  containing  a  lung,  over 
which  it  is  reflected,  passing  into  the  fissures.     This  reflec- 


324  A  MANUAL   OF  ANA  TOMY. 

tion  of  the  pleura  over  the  lung  is  the  visceral  layer.  The 
pleura  also  lines  the  interior  of  the  thorax,  diaphragm,  and 
sides  of  pericardium,  and  extends  upward  into  the  root  of 
the  neck  about  an  inch  above  the  clavicle ;  this  portion  is 
the  parietal  pleura.  These  layers  are  continuous  at  the 
root  of  the  lung,  and  between  them  is  the  pleural  cavity 
(not  a  cavity  unless  the  lungs  have  retracted  into  the  back 
of  the  chest).  From  the  root  of  the  lungs  a  fold  of  the 
pleura  descends  to  the  diaphragm  ;  this  is  the  broad  liga- 
ment of  the  lung. 

The  lower  level  of  the  pleural  reflection  from  the  dia- 
phragm on  to  the  chest  wall  has  been  given  on  page  264. 

The  Thymus  Gland. 

The  remains  of  this  structure  may  be  found  lying  below 
the  left  innominate  vein  and  over  the  transverse  arch  of 
the  aorta,  reaching  up  into  the  root  of  the  neck. 

The  Phrenic  Nerves.      Figs.  18,  69,  70,  72. 

Each  phrenic  nerve  is  formed  in  the  neck  by  branches 
from  the  anterior  divisions  of  the  third,  fourth,  and  fifth 
cervical  nerves.  It  descends  obliquely  downward  and  in- 
ward across  the  front  of  the  scalenus  anticus  muscle,  be- 
tween the  subclavian  artery  and  vein,  to  enter  the  thorax, 
passing  in  front  of  the  internal  mammary  artery. 

It  then  descends  to  the  diaphragm  under  cover  of  the 
pleura  ;  on  the  right  side  passing  along  the  outer  side  of 
the  right  innominate  vein,  superior  vena  cava,  and  the 
pericardium  ;  on  the  left  side,  it  is  to  the  outside  of  the 
transverse  aorta  and  behind  the  left  innominate  vein  ;  on 
both  sides  they  pass  in  front  of  the  roots  of  the  lungs, 
and  when  the  diaphragm  is  reached  pierce  it  and  are  dis- 
tributed to  the  under  side  of  the  muscle. 


11       10        9 


Fig.  68.  Dissection  of  the  Thorax.— i,  Left  internal  mamman'  artery.  2,  Left 
internal  mamniarv  vein.  3,  Left  subclavian  vein,  resting  upon  first  rib.  4,  Brachial  plexus. 
5,  Left  internal  jugular.  6,  Phrenic  nerve,  left.  7,  Left  pneumogastric  nerve.  8,  Left 
common  carotid  arterv.  9  and  11,  Inferior  thyroid  veins.  10,  Trachea.  12,  Right  internal 
jugular  vein.  13,  Right  subclavian  vein,  resting  upon  first  rib.  14,  Right  inferior  thyroid 
vein.  15,  Right  innominate  vein.  16,  Right  internal  mammary  artery.  17,  Right  internal 
mammary  vein.     i8.  Diaphragm.     19,  Eiisiform  appendix. 


326 


A  MANUAL   OF  ANATOMY. 


The  Innominate  Veins.     Figs.  68,  69,  70. 

Each  is  formed  by  the  internal  jugular  and  subclavian 
veins  behind  the  sternoclavicular  articulation.  The  right 
is  only  an  inch   long,  and  vertical  in  its  course  ;  the   left. 


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three  inches  long,  and  very  oblique  in  its  course ;  both 
veins  unite  in  the  first  intercostal  space  of  the  right  side 
close  to  the  sternum  and  form  the  superior  vena  cava. 


THE  THORAX.  327 

Relations. — Right :  In  front,  sternal  origins  of  the  sterno- 
hyoid and  sternothyroid  muscles,  clavicle,  first  costal  carti- 
lage, and  remains  of  the  thymus  gland  ;  behind,  pleura 
and  lung  ;  to  the  right,  pleura,  lung,  and  phrenic  nerve 
(right)  ;  to  the  left,  right  subclavian  artery  and  pneumo- 
gastric  nerve,  the  innominate  artery,  and  trachea. 

The  left :  In  front,  sternohyoid  and  sternothyroid  mus- 
cles, manubrium,  clavicle,  sternoclavicular  articulation,  re- 
mains of  thymus  gland  ;  behind,  innominate,  left  carotid 
and  subclavian  arteries,  trachea,  left  phrenic  nerve,  left 
pneumogastric  nerve ;  below,  the  transverse  aorta  ;  above, 
the  cervical  fascia  and  inferior  thyroid  veins. 

Tributaries. — Both  receive  the  internal  jugular,  subcla- 
vian, vertebral,  deep  cervical,  and  inferior  thyroid  veins 
above,  and  the  internal  mammary  below.  The  left  vein 
also  receives  the  left  superior  intercostal,  thymic,  medias- 
tinal, pericardiac  veins,  and  the  thoracic  duct ;  the  right, 
the  right  lymphatic  duct.  The  ducts  empty  into  the  in- 
nominate veins  at  the  junction  of  the  internal  jugular  and 
subclavian. 

The  Superior  Vena  Cava.      Fig.  70.      Diags.  21,  22. 

This  is  formed  in  the  first  intercostal  space  close  to  the 
right  side  of  the  sternum  by  the  junction  of  the  right  and 
left  innominate  veins.  Its  course  is  downward  to  the  right 
auricle  of  the  heart,  into  which  it  opens. 

Relations. — In  front,  first  and  second  intercostal  spaces 
and  the  second  costal  cartilage,  remains  of  the  thymus 
gland,  pericardium,  pleura,  and  right  lung  ;  behind,  azygos 
major,  right  bronchus,  right  pulmonary  artery,  and  right 
superior  pulmonary  vein,  the  pericardium  ;  to  the  right, 
phrenic  nerve,  lung,  and  pleura ;  to  the  left,  ascending 
aorta,  innominate  artery. 


328  A  MANUAL   OF  ANATOMY. 

Tributaries. — The  right  and  left  innominate  veins,  azygos 
major,  mediastinal  and  pericardial  veins. 

The  arteria  comes  nervi  phrenici  is  a  very  small 
artery  from  the  internal  mammary  to  the  phrenic  nerve 
just  after  the  latter  crosses  the  former.  It  accompanies 
the  nerve  to  the  diaphragm. 


DISSECTION. 

Make  a  vertical  and  a  transverse  incision  in  the  pericardium. 
Reflect  the  flaps  ;  study  the  situation  and  relations  of  the  heart  and  its 
great  vessels. 

The  Pericardium.     Figs.  68,  69. 

The  pericardium  is  a  fibrous  sack  enclosing  the  heart 
and  beginning  of  the  great  vessels.  Below  it  is  attached 
to  the  central  tendon  of  the  diaphragm,  mostly  at  the  left, 
of  the  median  line  ;  above  it  passes  on  to  the  great  vessels 
and  becomes  continuous  with  the  deep  cervical  fascia  from 
the  neck. 

The  fibrous  pericardium  is  lined  by  a  serous  layer  that 
is  also  reflected  on  to  the  heart  and  beginning  of  the  great 
vessels.  The  portion  of  the  serous  membrane  lining  the 
sack  is  the  parietal,  that  reflected  over  the  vessels  and 
heart  is  the  visceral  layer. 

The  serous  layer  extends  upward  on  to  the  beginning  of 
the  great  vessels  for  a  distance  of  one  or  one  and  one-half 
inches  from  the  base  of  the  heart. 

Relations. — In  front,  sternum  and  cartilages  from  third 
to  the  sixth  inclusive,  anterior  intercostal  muscles,  trian- 
gularis sterni,  to  some  extent  by  the  lungs  and  pleurae  ; 
laterally,  pleurse,  lungs,  phrenic  nerves,  and  accompany- 
ing arteries ;  posteriorly,  bronchi,  oesophagus,  pneumo- 
gastric  nerves,  descending  aorta  ;    below,  the  diaphragm, 


Fig.  69.  Dissection  of  the  Thorax. — The  lungs  are  separated  to  show  the  peri- 
cardium, its  extension  upon  the  great  vessels  of  the  heart,  and  the  course  of  the  phrenic 
nerves.     The  structures  are  the  same  as  in  the  preceding  figure. 


330  A  MANUAL   OF  ANATOMY. 

to  which   it  is  attached.      Above  it  is  continuous  with  the 
deep  cervical  fascia  on  the  great  vessels. 

Contents  of  the  Pericardiiun. — Heart  (its  auricles,  ventri- 
cles, arteries,  veins,  and  nerves),  ascending  aorta,  pulmo- 
nary artery,  pulmonary  veins,  superior  vena  cava. 

The  Heart.     Figs.  57,  58,  68  to  73. 

Is  a  hollow  muscular  cone,  placed  with  its  base  upward, 
backward,  and  to  the  right,  and  its  apex  downward,  for- 
ward, and  to  the  left.  For  the  surface  relations  consult 
description  already  given. 

Its  dimensions  :  Length,  5  inches  ;  breadth,  3  i/^  inches  ; 
thickness,  2^  inches  ;  weight,  1 1  ounces  in  the  male,  9  in 
the  female. 

The  heart  is  attached  by  its  base  to  the  great  vessels 
which  proceed  from  it.  Its  apex  is  free  and  in  life  describes 
considerable  movement. 

It  is  divided  into  four  cavities  by  two  partitions,  one 
between  the  ventricles,  the  interventricular,  one  between 
the  auricles  and  ventricles,  the  auriculoventricular. 

The  location  of  the  partitions  is  indicated  on  the  outside 
of  the  heart  by  grooves,  the  auriculoventricular  groove 
being  deeper  and  better  marked  than  the  interventricular. 
The  former  is  obliterated  in  front  by  the  pulmonary  artery. 
The  heart  (and  vessels  for  their  first  one  and  a  half  inch)  is 
covered  by  the  visceral  layer  of  the  pericardium,  and  its 
cavities  are  lined  by  a  similar  smooth  membrane — the  endo- 
cardium— continuous  with  the  lining  of  the  blood  vessels. 

On  opening  the  pericardium  the  greater  part  of  the  heart 
presenting  is  composed  of  the  right  ventricle  and  auricle  ; 
the  smaller  part,  of  the  left  ventricle  and  auricle.  The 
ascending  aorta,  pulmonary  artery,  and  superior  vena  cava 
are  also  in  view. 


Fig.  70.  Dissection  of  Thorax.— a,  Right  ventricle,  b,  Left  ventricle,  c,  Right 
auricle,  rf,  Pulmonary  artery.  ^.  Ascendingaorta.  /,  Superior  vena  cava.  ^,  Left  coro- 
nary artery  and  vein.  h.  Right  marginal  artery  and  vein  ;  anterior  branch  of  right  coro- 
nary artery,  t,  Pericardium  ;  inner  surface.  Note  the  diff"erence  between  the  external 
and  internal  appearaiice  of  the  pericardium.  Also  the  notch  at  the  apex  of  the  heart 
where  the  ventricles  meet. 


332  A  MANUAL   OF  ANA  TO  MY. 

The  dissection  of  the  heart,  see  page  354. 

The  Pulmonary  Artery.  Figs.  57,  58,  70  to  73.  Diag. 
22. 

Conveys  the  venous  blood  from  the  right  heart  to  the 
lungs.  It  is  about  two  inches  long,  and  is  contained  within 
the  pericardium,  and  ends  by  dividing  into  two  terminal 
branches,  which  pass  through  the  pericardium. 

It  presents  in  the  interval  between  the  two  auricles, 
curves  upward,  to  the  left,  and  backward  beneath  the  aortic 
arch,  to  which  it  is  attached  by  the  obliterated  ductus 
arteriosus  (remains  of  the  foetal  communication  between 
the  pulmonary  artery  and  the  aorta),  where  it  divides  into 
its  two  terminal  branches. 

Relations. — At  the  beginning  it  is  between  the  two  auri- 
cles, and  has  the  ascending  aorta  behind  and  to  the  right. 
The  coronary  arteries  are  on  either  side  of  it.  It  is  covered 
by  the  pericardium.  At  its  termination  it  Hes  beneath  the 
aortic  arch,  to  the  left  of  the  ascending  aorta,  and  over  the 
left  auricle,  and  is  covered  by  pericardium  on  the  left. 

(See  page  352  for  dissection.) 

The  Ductus  Arteriosus.      Fig.  72. 

This  is  the  fibrous  cord  in  the  adult  which  is  found 
joining  the  under  surface  of  the  transverse  aorta  to  the 
upper  surface  of  the  pulmonary  artery.  In  the  foetus  it 
was  relatively  a  large  trunk  and  conducted  the  blood  from 
the  pulmonary  artery  into  the  aorta. 

The  Right  Pulmonary  Artery. 

Is  longer  than  the  left,  passes  to  the  right  lung,  where  it 
divides  into  three  main  branches  to  the  three  lobes. 

Relations. — In  front,  ascending  aorta,  superior  vena  cava, 
phrenic  nerve,  and  anterior  pulmonary  plexus   of  nerves  ; 


2019181716 


1234        56  78  9     10  11     12  13 


Fig.  71.  Dissection  of  Thorax.— <z,  Right  auricle,  b.  Right  ventricle,  c,  Left 
ventricle,  d,  Left  auricle,  e,  Pulmonary  artery  /",  Ascendino;  aorta,  g.  Transverse 
aorta,  h,  Superior  vena  cava.  /,  Left  corona'-y  artery.  /,  Right  marginal  artery  from 
right  coronary,  /fe,  Innominate  artery,  i,  Left  recurrent  laryngeal  nerve.  The  reference 
line  crosses  the  trachea.  2,  Oesophagus.  3,  Left  pneumogastric  nerve.  4,  Vertebral 
artery.  5,  6,  7,8,  and  9,  Nerves  going  to  form  the  brachial  ple.xus.  10,  ii,  and  12,  The 
outer,  middle,  and  imier  cords.  13,  Scalenus  medius  muscle  ;  also  first  rib.  14,  Left  com- 
mon carotid  artery.  15,  Left  subclavian  artery.  16,  16,  Right  pneumogastric  nerve.  17, 
The  ascending  cervical  artery.  18,  Right  phrenic  nerve.  19,  Right  common  carotid  20, 
Transverse  cervical  artery.  21,  Brachial  plexus.  22,  Scalenus  anticus  muscle.  27,,  Right 
axillarv  arterv.  24,  Right  subclavian  artery.  25,  Internal  mammary  artery.  26,  Upper 
lobe  of  right  lung.  27,  The  lower  lobe  of  the  same.  28,  29,  The  diaphragm.  30,  Pulmo- 
nary artery.     31,  Bronchus.    32,  Pulmonary  veins. 


334  A  MANUAL  OF  ANATOMY. 

behind,   right  bronchus ;   above,  transverse  aorta  ;  below, 
the  left  auricle. 

In  the  root  of  the  lung  it  is  between  the  bronchus  (above) 
and  the  pulmonary  veins  (below)  ;  behind  is  the  azygos 
vein,  pneumogastric  nerve,  and  posterior  pulmonary  plexus. 

The  Left  Pulmonary  Artery. 

Is  shorter  than  the  right,  reaches  to  the  left  lung,  and 
divides  into  two  branches. 

Relations. — In  front,  phrenic  nerve,  anterior  pulmonary 
plexus,  left  pleura  ;  behind,  descending  aorta,  left  pneumo- 
gastric nerve,  posterior  pulmonary  plexus  ;  below  (and  in 
front),  pulmonary  veins,  left  bronchus. 

The  Aorta.  (The  description  will  be  given  here  in  full. 
For  dissection  see  page  352).     Figs.  57,  58,  69  to  74. 

The  outlet  for  the  blood  from  the  left  ventricle. 

In  the  subject  is  seen  to  be  contained  in  the  pericardium 
for  its  first  two  inches  (or  less).  It  presents  to  the  right 
of  and  behind  the  pulmonary  artery  and  right  auricle.  Its 
direction  is  upward,  backward,  and  to  the  left,  then  down- 
ward along  the  spinal  column  to  leave  the  thorax  through 
the  aortic  opening.  It  is  divided  into  the  ascending,  trans- 
verse, descending,  and  thoracic  portions. 

The  Ascending-  Aorta.     Diag.  22. 

This  is  about  two  inches  long.  It  begins  at  the  left 
ventricle  of  the  heart,  passes  upward,  curving  slightly 
to  the  right  in  its  course  ;  it  ends  where  the  artery  turns 
to  pass  transversely  into  the  left  portion  of  the  thorax. 
From  its  base  on  the  right  and  left  sides  are  given  off 
the  coronary  arteries  to  the  heart,  the  left  coronary  artery 
supplying  the  left  ventricle  mostly,  and  the  right,  the  right 
ventricle.     At  the  base  of  the  aorta  it  is  dilated  into  three 


THE  THORAX. 


335 


pouches  forming  the  sinuses  of  Valsalva,  one  in  front 
and  two  posterior. 


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o  g 

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Relations. — In  front  is  the  pericardium  (and  the  structures 
that  overlie  the  pericardium  in  the  middle  line). 

At  its  base  the  pulmonary  artery  :  Behind,  left  auricle  of 
heart,    right   pulmonary    artery,    right   bronchus,  anterior 


336 


A  MANUAL   OF  ANATOMY. 


cardiac  nerves  ;  at  the  right,  right  auricle  and  superior  vena 
cava ;  at  the  left,  pulmonary  artery  and  cardiac  nerves. 

The  Transverse  Aorta.      Diag.  2i. 

This  is  nearly  two  inches  long,  also.    Takes  a  course  back- 


ward and  to  the  left  from  the  level  of  the  second  right  carti- 
lage (or  the  first  intercostal  space)  to  the  body  of  the  fourth 
(or  third)  dorsal  vertebra  on  the  left  side.     The  highest  por- 


From  the  Second  Prize  Dissection  at  the  University  Medical  College,  for  1895, 
by  P.  D.  Shtiltz. 

Fig.  72.  Dissection  op- THE  Thorax. — a,  Right  auricle.  6,  Right  ventricle,  c,  Left 
ventricle,  d.  Left  auricle,  e.  Pulmonary  artery  f.  Ascending  aorta,  g.  Transverse 
aorta,  h.  Descending  aorta,  i.  Thoracic  aorta.  From  it  the  left  intercostal  arteries  are 
shown,  y,  Pericardium,  k,  Left  coronary  artery.  /,  Left  pulmonary  artery,  vi.  Left 
bronchus.  «,  Innominate  artery,  o,  Left  common  carotid.  ^,  Left  suhclavian  artery,  q. 
Ductus  arteriosus,  i,  Thyroid  cartilage.  2,  Trachea.  3,  3,  Left  pneumogastric  nerve.  4, 
Left  sympathetic  cord.  5,  5,  Left  phrenic  nerve.  6,  Left  subclavian  artery.  7,  Scalenus 
anticus  muscle.     8,  Internal  mammary  artery,  left.     9,  Left  recurrent  laryngeal. 


22 


338  A  MANUAL  OF  A  ANATOMY. 

tion  of  the  under  surface  of  the  arch  is  opposite  the  articu- 
lation between  the  first  and  second  portions  of  the  sternum. 
From  its  upper  surface  it  gives  off  the  innominate,  left  com- 
mon carotid,  and  subclavian  arteries. 

Relations. — In  front,  pleurae  and  lungs  (in  inspiration), 
left  phrenic  and  pneumogastric  and  cardiac  nerves,  and  the 
left  superior  intercostal  vein ;  behind,  trachea,  oesophagus, 
thoracic  duct,  deep  cardiac  plexus,  left  recurrent  laryngeal 
nerve  ;  above,  its  three  branches  and  the  left  innominate 
vein  ;  below,  left  bronchus,  bifurcation  of  pulmonary 
■artery,  left  recurrent  laryngeal  nerve,  remains  of  ductus 
arteriosus,  some  lymphatic  glands. 

The  Descending-  Aorta.      Diag.  22, 

This  continues  the  arterial  vessel  from  the  ending  of  the 
transverse  aorta  (see  above)  to  the  level  of  the  lower  bor- 
der of  the  fifth  dorsal  vertebra,  where  it  becomes  the 
thoracic  aorta. 

Relations. — In  front,  left  lung  and  pleura  covering  it ; 
behind,  left  side  of  the  (third),  fourth,  and  fifth  vertebrae  ; 
at  the  right,  oesophagus,  thoracic  duct,  and  the  above 
vertebrae  ;   at  the  left,  lung  covered  by  its  pleura. 

The  Thoracic  Aorta.      Diags.  22,  23.      Figs.  72,  74. 

Is  the  continuation  of  the  aorta  from  its  descending  por- 
tion (see  above)  along  the  front  of  the  dorsal  vertebrae  to 
the  twelfth,  where  it  leaves  the  thorax  by  passing  through 
the  aortic  opening  in  the  diaphragm  into  the  abdomen. 
At  its  beginning  it  is  a  little  to  the  left  of  the  middle  line, 
but  at  its  ending  is  over  the  middle  line.  It  is  one  of  the 
constituents  of  the  posterior  mediastinum. 

Relations. — In  front,  root  of  left  lung,  oesophagus,  dia- 
phragm ;  behind,  the  dorsal  vertebrae  from  the  fifth  to  the 
twelfth    inclusive,   vena   azygos   minor  (at   the   seventh   or 


THE  THORAX. 


339 


eighth),  superior  intercostal  vein  (at  the  fifth  or  sixth 
vertebn-e)  ;  at  the  left,  left  lung  and  pleura,  the  oesopha- 
gus ;  at  the  right,  the  thoracic  duct.  For  relations  of 
oesophagus  to  artery,  see  page  343. 

The  Innominate  Artery.      Fig.  71.      Diag.  20. 

It  arises  from  the   transverse  aorta  near  its  beginning, 
passes   upward   and   outward  to   behind   the  right  sterno- 


Diag.  23.  Transverse  Section  of  the  Thorax  just  Above  the  Diaphragm. 
(/.  6'.  H.)—i.  Left  pneumogastric  tierve.  2,  Right  pneumogastric  nerve.  3,  Thoracic 
duct.    4,  Azygos  major,  and  5,  Minor  veins. 


clavicular  articulation,  where  it  divides  into  the  right  com- 
mon carotid  and  subclavian  arteries.  Its  length  is  from 
one  and  one-half  to  two  inches. 

Relations. — In  front,  first  piece  of  the  sternum,  origins 
of  the  right  sternohyoid  and  sternothyroid  muscles,  right 
sternoclavicular  joint,  remains  of  thymus  gland,  left  in- 
nominate and  inferior  thyroid  veins,  right  cardiac  nerves  ; 


340  A  MANUAL  OF  ANA  TOMY. 

behind,  trachea,  right  lung,  and  pleura ;  at  the  right, 
right  innominate  vein,  right  pneumogastric  nerve,  right 
lung  and  pleura;  at  the  left,  left  common  carotid  artery : 
at  the  ending  of  the  artery,  the  trachea. 

Thoracic  portions  of  the  left  common  carotid  and  sub- 
clavian arteries  : — 

The  Left  Cominon  Carotid.     Fig.  7 1 .     Diag.  20. 

Arises  from  the  middle  of  the  upper  surface  of  the 
transverse  aorta,  passes  upward  and  outward  into  the  neck. 
For  rest  of  course  see  page  loi. 

Relations  (within  thorax). — In  front,  manubrium,  origins 
of  the  left  sternohyoid  and  sternothyroid  muscles,  remains 
of  thymus  gland,  left  innominate  vein  ;  behind  (and  from 
below  upward),  trachea,  oesophagus,  thoracic  duct,  recur- 
rent laryngeal  nerve  ;  at  the  right,  innominate  artery, 
trachea,  inferior  thyroid  veins  ;  at  the  left,  left  subclavian 
artery  (behind),  left  pneumogastric  nerve,  left  lung  and 
pleura. 

The  Left  Subclavian  Artery.     Figs.  70,  71.     Diag.  20. 

Is  given  off  the  transverse  aorta  at  its  terminus,  extends 
almost  vertically  upward  into  the  neck,  passing  behind  the 
left  sternoclavicular  articulation. 

Relations  (within  the  thorax).  In  front  :  First  left  costal 
cartilage  and  adjacent  portions  of  manubrium,  left  sterno- 
clavicular joint,  origins  of  the  left  sternohyoid  and  sterno- 
thyroid muscles,  left  lung  and  pleura,  left  innominate  vein, 
left  pneumogastric  and  cardiac  nerves.  Behind  :  Thoracic 
duct,  longus  colli  muscle,  vertebrae.  At  the  right :  Left 
common  carotid  (in  front),  trachea,  left  recurrent  laryngeal 
nerve,  oesophagus  (behind). 

For  the  continuation  of  the  artery  see  page  108. 


Pig-  73-  Heart  and  Root  of  Lungs  from  Behind.— a,  a,  a,  a,  Right  pulmonary 
artery  and  its  branches,  b,  b,  Upper  and  lower  divisions  of  right  bronchus,  c,  c,  c,  Right 
pulmonary  veins,  rf,  Vena  azygos  major,  e,  Right  bronchus,  y",  Trachea.  ^,  Left  bron- 
chus, h,  Innominate  artery,  i.  Left  common  carotid  artery,  j.  Left  subclavian  artery. 
k,  Descending  aorta.  /,  Left  innominate  vein,  m,  Left  pulmonary  artery,  n.  Left  bron- 
chus, o,  Left  pulmonary  vein.  /,  Posterior  surface  of  left  auricle,  q,  Orifice  of  inferior 
vena  cava,    r,  Left  ventricle,    s,  Right  ventricle,    t,  Coronary  sinus. 


342  A  MANUAL   OF  ANA  TOMY. 

The  Pneumo gastric  Nerves.     Figs.  i8,  71,  72. 

Are  found  in  the  neck  between  the  internal  jugular  vein 
and  the  common  carotid  artery,  and  behind  both.  See 
page  103. 

The  right  nerve  comes  forward  between  the  vein  and 
artery,  crosses  over  the  front  of  the  subclavian  artery  and 
behind  the  right  innominate  vein  (gives  off  the  recurrent 
laryngeal  nerve  opposite  the  lower  part  of  the  artery),  and 
descends  backward  and  inward  to  the  side  of  the  oesophagus 
and  behind  the  root  of  the  lung,  where  it  forms  the  posterior 
pulmonary  plexus.  From  the  plexus  it  is  continued  by 
two  branches  along  the  posterior  surface  of  the  oesophagus 
(forming  the  oesophageal  plexus)  ;  finally  these  two  cords 
unite,  pass  through  the  diaphragm,  and  are  distributed  to 
the  posterior  wall  of  the  stomach. 

The  left  pneumogastric  at  the  base  of  the  neck  is  be- 
tween the  left  common  carotid  and  subclavian  arteries, 
descends  behind  the  left  innominate  vein,  over  the  front  of 
the  transverse  aorta  (at  the  lower  border  of  which  the  left 
recurrent  laryngeal  nerve  is  given  off),  to  the  posterior  part 
of  the  root  of  the  left  lung,  where  it  forms  a  posterior  pul- 
monary plexus.  It  then  continues  along  the  front  of  the 
oesophagus  by  two  branches  (forming  an  oesophageal  plexus 
and  communicating  with  the  posterior  plexus  by  branches), 
then  these  two  branches  unite  and  pass  through  the  dia- 
phragm to  the  anterior  wall  of  the  stomach. 

The  Right  Recurrent  Laryngeal  Nerve.     See  Neck,  page 
104. 

The  Left  Recurrent  Laryngeal. 

Can  be  traced  curving  around  the  transverse  aorta,  ex- 
ternal to  the  ductus  arteriosus  and  above  the  pulmonary 
artery,  to  pass  upward  and  inward  behind  the  left  common 


THE  THORAX.  343 

carotid,  and  ascend  in  the  interval  between  the  trachea  and 
the  oesopliagLis  into  the  neck,  q.  v.,  page  104. 

DISSECTION. 

If  the  innominate  veins  have  been  tied  off,  proceed  with  the  following  (if 
they  have  not,  then  tie  them  off  close  to  the  superior  vena  cava)  : — 

Divide  the  branches  of  the  aorta  (or  if  they  have  been  cut  away  in  the 
neck,  remove  the  attached  portions  with  the  aortic  arch),  divide  the  trachea 
at  the  opening  of  the  chest,  the  phrenic,  pneumogastric,  and  the  recurrent 
(left)  laryngeal  nerves.  Lift  everything  forward  and  cut  the  aorta  across  at 
the  beginning  of  its  downward  curve.  Separate  the  trachea  from  the  oesoph- 
agus, divide  the  azygos  major  close  to  the  superior  cava,  sever  the  attachments 
of  the  pericardium  to  the  diaphragm,  divide  the  inferior  vena  cava,  and  re- 
move the  heart,  great  vessels,  adherent  portions  of  nerves  and  veins,  and  the 
trachea  and  lungs  from  the  thoracic  cavity. 

Place  these  parts  into  a  common  salt  solution  for  later  dissection. 

Turn  to  the  interior  of  the  thorax. 

The  CEsophag-us.      See  page  124.      Diags.  20  to  23. 

Begins  in  front  of  the  fifth  cervical  vertebra  and  behind 
the  cricoid  cartilage,  nearly  in  the  median  line.  It  enters 
the  upper  opening  of  the  chest  a  little  to  the  left  of  the 
middle  line  and  in  front  of  the  bodies  of  the  vertebra,  de- 
scends to  the  oesophageal  opening  in  the  diaphragm,  and 
terminates  in  the  stomach.  In  its  course  the  thoracic  duct 
intervenes  between  it  and  the  bodies  of  the  vertebrae  above 
and  the  thoracic  aorta  below.  Its  length  is  from  nine  to 
eleven  inches. 

Relations. — In  the  neck  :  In  front,  trachea.  Laterally, 
the  lobes  of  the  thyroid  gland,  the  recurrent  laryngeal 
nerves,  common  carotid  and  inferior  thyroid  arteries,  thor- 
acic duct  (at  the  left).  Behind,  prevertebral  fascia,  longus 
colli  muscle,  lower  cervical  vertebrae  (below  the  fifth). 

In  the  thorax  :  In  front,  trachea,  left  common  carotid 
and  subclavian  arteries,  left  bronchus,  transverse  aorta, 
pericardium,    left   pneumogastric    nerve.      Laterally,  pneu- 


344  A  MANUAL   OF  ANATOMY. 

mogastric  nerves,  pleural  sacs,  and  lungs.  Aorta  at  left 
and  vena  azygos  major  at  right.  Behind,  longus  colli  muscle, 
dorsal  vertebrae,  thoracic  duct,  third,  fourth,  and  fifth  right 
intercostal  arteries,  left  lower  azygos  vein,  aorta,  right 
pneumogastric  nerve. 

DISSECTION. 
Remove  the  oesophagus,  tying  a  cord  around  its  lower  end  as  it  passes 
through  the  diaphragm. 

The  Thoracic  Duct.      Diags.  20  to  23. 

This  begins  in  the  abdomen  as  the  duct  of  the  recepta- 
culum  chyli  in  front  of  the  first  and  second  lumbar  vertebrae 
and  behind  the  abdominal  aorta. 

The  duct  passes  into  the  thorax  through  the  aortic  open- 
ing at  the  right  of  the  artery,  and  then  along  the  front  of 
the  spine,  between  the  thoracic  aorta  on  the  left  and  the 
vena  azygos  major  on  the  right,  until  at  the  third  dorsal 
vertebra  it  turns  to  the  left  behind  the  aortic  arch  and 
oesophagus.  It  passes  upward  at  the  left  of  the  latter  into  the 
neck,  arches  over  the  left  subclavian  artery  and  the  apex  of 
the  left  lung  to  empty  into  the  junction  of  the  left  jugular 
and  subclavian  as  they  are  forming  the  left  innominate  vein. 

At  its  opening  into  the  vein  there  are  two  valves  found. 
Other  valves  similar  to  those  found  in  the  veins  are  dis- 
tributed throughout  its  length.  It  is  about  fifteen  or 
eighteen  inches  long,  and  in  diameter  varies  from  one-fourth 
to  one-sixth  of  an  inch. 

The  thoracic  duct  receives  the  drainage  from  the  lower 
extremities,  abdominal  organs  (excepting  the  upper  surface 
of  the  liver  and  abdominal  walls),  left  lung,  left  side  of  the 
heart,  left  upper  extremity,  and  left  side  of  the  head  and  neck. 
It  empties  all  this  collection  into  the  beginning  of  the  left 
innominate  vein. 


THE  THORAX.  345 

Tlic  Tlioracic  Sympathetic  Nen'ous  System.     Fig.  74. 

This  consists  of  a  nerve  cord  which  extends  through  the 
chest  alongside  of  the  dorsal  vertebrae  (continuous  above  with 
the  cervical  and  below  with  the  lumbar  cord),  and  a  series 
of  enlargements  or  ganglia,  twelve  in  number,  which  rest 
upon  the  heads  of  the  ribs  (excepting  the  last  two,  which 
lie  upon  the  side  of  the  body  of  the  corresponding  ver- 
tebrae). 

The  sympathetic  branches  are  (external)  to  the  intercostal 
nerves  and  (internal)  to  the  thoracic  viscera. 

From  the  lower  ganglia  are  given  off  the  important 
splanchnic  nerves,  which,  formed  in  the  thorax,  pass  to  the 
abdomen. 

(i)  The  great  splanchnic  nerve  is  formed  by  filaments 
from  the  fifth  to  the  ninth  thoracic  ganglia  inclusive,  passes 
through  the  crus  of  the  diaphragm,  and  terminates  in  the 
semilunar  ganglion  of  that  side.  (2)  The  lesser  splanchnic 
nerve  is  composed  of  filaments  from  the  eleventh  and 
twelfth  ganglia,  takes  the  same  course  through  the  diaph- 
ragm as  the  great,  and  ends  in  the  solar  or  renal  plexus. 
(3)  The  smallest  splanchnic  nerve  is  a  small  branch  from  the 
last  thoracic  ganglia  to  the  renal  plexus. 

TJie  Branches  of  the  Thoracic  Aorta.  (For  the  artery  see 
page  338.)     Figs.  72,  74. 

(i)  Pericardial,  a  few  small  arteries  to  the  posterior  sur- 
face of  the  pericardium.  (2)  Bronchial,  three  in  number. 
The  right  usually  rises  from  the  first  right  (aortic)  intercos- 
tal artery  or  from  the  front  of  the  thoracic  aorta  by  a  trunk 
common  to  it  and  the  left  upper  bronchial  artery.  It  runs 
outward  to  the  right  lung  on  the  back  of  the  bronchus.  The 
left  bronchial  are  two  in  number,  arising  from  the  thoracic 
aorta  one  below  the  other,  and  both  pass  to  the  left  lung 
along  the  back  of  the  bronchus.     The  left  upper  may  arise 


346  A  MANUAL   OF  ANATOMY. 

by  the  common  trunk  from  the  first  right  intercostal 
artery.  The  bronchial  arteries  supply  the  lungs,  lym- 
phatic glands  (bronchial),  oesophagus,  and  pericardium. 
(3)  The  oesophageal,  four  or  five  to  the  oesophagus  and 
mediastinum.  (4)  The  intercostal  arteries.  There  are  nine 
or  ten  of  these  distributed  to  the  parietes  of  the  chest.  The 
first  and  second  spaces  are  supplied  by  the  superior  inter- 
costal branch  of  the  subclavian  (seepage  113).  The  right 
intercostals  are  slightly  longer  than  the  left,  owing  to  the  dis- 
placement of  the  aorta  to  the  left  of  the  median  line.  Their 
course  is  alike  in  all.  Each  artery  runs  outward,  with  the 
intercostal  vein  above  and  the  nerve  below,  upon  the  exter- 
nal intercostal  muscle,  then  between  the  external  and  inter- 
nal intercostal  muscles,  and  in  the  intercostal  groove  of  the 
rib  above  ;  passing  around  the  chest  to  the  front,  it  finally 
anastomoses  with  the  upper  of  the  pair  of  anterior  intercos- 
tal arteries  from  the  internal  mammary.  The  lower  inter- 
costal arteries  anastomose  with  the  musculophrenic  branch 
of  the  internal  mammary  and  the  upper  lumbar  arteries. 
Each  intercostal  artery  gives  off  a  dorsal  artery  to  the  parts 
posterior  to  the  chest,  and  a  branch  to  the  spine  and  cord. 
Also,  a  small  collateral  intercostal  artery  opposite  the  angle 
of  the  ribs.  This  artery  runs  forward  along  the  top  of  the 
rib  below  and  between  the  external  and  internal  intercostal 
muscles  to  anastomose  in  front  with  the  lower  of  the  pair  of 
anterior  intercostal  arteries  from  the  internal  mammary. 
(5)  The  pleural,  muscular,  and  mammary  (from  the  third, 
fourth,  and  fifth)  are  small  branches  from  the  intercostals. 

The  Intercostal  Muscles. 

The  External. 

Origin. — From  the  lower  outer  border  of  the  upper  eleven 
ribs  external  to  the  tubercles. 


THE  THORAX.  347 

Insertion. — Into  the  upper  border  of  the  eleven  lower  ribs 
a  little  external  to  the  tubercles.  Three  or  four  of  the 
lower  muscles  reach  into  the  cartilages  for.  their  insertion. 
The  direction  of  the  fibres  is  from  above  downward  and 
forward. 

The   Internal. 

Origin. — From  the  inner  border  of  the  intercostal  groove 
of  the  eleven  upper  ribs  and  cartilages  ;  from  the  sternum 
around  to  the  angles  of  the  ribs. 

Insertion. — The  fibres  pass  downward  and  backward  to 
the  upper  surface  of  the  rib  and  cartilage  below. 

Nerve  Supply. — The  intercostal  nerves. 

Action. — The  intercostal  muscles  act  to  bring  together  the 
ribs  between  which  they  are  placed.  The  external  inter- 
costals  act  upon  the  ribs  alone,  the  internal  upon  the  ribs 
and  cartilages.  Taken  together,  the  action  of  the  intercostal 
muscles  is  to  elevate  the  ribs  and  cartilages.  From  this 
action  two  results  follow. 

The  chest  is  enlarged  in  two  directions,  transversely  and 
anteroposteriorly.  But  this  is  not  secured  by  the  move- 
ment of  the  ribs  upon  two  axes,  as  stated  by  most  authori- 
ties ;  such  an  explanation  is  not  warranted  by  the  construc- 
tion of  the  joints  which  unite  the  ribs  to  the  spinal  column. 
The  reasons  for  the  enlargement  are  these  :  First,  the  ribs 
move  upon  an  axis  passing  through  their  heads  and 
tubercles.  This  allows  the  rib  to  move  as  if  hinged  at  these 
points,  and  the  anterior  end  moves  upward  and  downward. 
Second,  the  ribs  increase  in  size  from  above  downward 
(until  the  seventh  rib  is  met  with).  Third,  the  ribs  are  not 
placed  horizontally,  but  slope  from  behind  downward  and 
forward.  Fourth,  when  the  intercostal  muscles  act,  they 
raise  the  ribs  and   cartilages  into  a  more  nearly  horizontal 


348  A  MANUAL  OF  ANA  TOMY. 

position.  Now  this  action  substitutes  a  rib  oi  greater  for  one 
of  less  dimensions,  and  the  result  is  to  increase  the  dimen- 
sions of  the  chest  transversely ,  and  anteroposteriorly  by  an 
amount  equal  to  the  difference  between  the  areas  of  the 
sections  of  the  thorax  at  the  level  of  these  two  ribs. 

The  Intercostal  Veins.     Fig.  74. 

These  veins  accompany  the  intercostal  arteries  and  re- 
turn the  blood  from  the  area  which  they  supply.  They 
terminate  by  emptying  into  the  veins  described  below. 

The  Azygos  Veins.     Figs.  74,  73. 

These  present  numerous  variations  in  formation,  course, 
and  termination,  but  the  following  arrangement  is  the  one 
usually  found. 

(i)  The  azygos  major  begins  in  the  abdomen  as  a  con- 
tinuation of  the  ascending  lumbar  vein,  or  by  a  branch 
from  the  right  renal,  or  vena  cava  inferior.  It  enters  the 
chest  through  the  aortic  opening,  lies  to  the  right  of  the 
aorta  upon  the  intercostal  arteries  and  vertebrae,  and  at  the 
level  of  the  third  or  fourth  dorsal  vertebra  arches  over  the 
right  bronchus  and  empties  into  the  superior  vena  cava 
(now  removed)  close  to  its  pericardial  attachment.  It  re- 
ceives the  nine  or  ten  lower  right  intercostal  veins,  the 
azygos  minor  (opposite  the  sixth  or  seventh  dorsal  verte- 
bra), the  right  superior  intercostal  vein,  the  left  azygos 
superior  (at  times),  the  right  mediastinal,  bronchial,  spinal, 
and  oesophageal  veins. 

(2)  The  azygos  minor  also  begins  in  the  abdomen  from 
the  left  renal  or  ascending  lumbar  veins,  enters  the  chest 
through  the  left  crus  of  the  diaphragm,  ascends  at  the  left  of 
the  vertebrae  to  the  level  of  the  seventh  or  eighth,  then  turns 
to  the  right  under  the  aorta  to  empty  into  the  major  azygos 
at  the  level  of  the  sixth  or  seventh  vertebra.     The  minor 


Fig.  74.  Dissection  of  Thorax  Cand  Abdomen).—!,  Right  subclavian  artery.  2,  Thoracic 
aorta  and  its  intercostal  branches  on  the  right  side.  3,  Vena  azygos  major  and  its  tributaries. 
4.  Point  where  the  vena  azvgos  minor  empties  into  the  major.  5,  Remains  of  diaphragm.  6, 
Coeliac  axis.  7,  The  right  semilunar  ganglion.  This,  with  the  left,  forms  a  plexus  (the  solar) 
about  the  cceliac  axis.  8,  Superior  mesenteric  arten,-.  9,  Right  suprarenal  artery.  10,  Right 
renal  artery.  11,  Abdominal  aorta  12,  Right  crus  of  diaphragm.  13.  Right  spermatic  artery. 
14,  One  of  the  right  lumbar  arteries.  The  others  are  also  shown,  but  not  named.  15,  Right,  and 
16.  Left  common  iliac  arteries.  17,  Right  axillary  artery.  18,  Right  superior  intercostal  artery. 
19,  Thoracic  sympathetic  cord  and  ganglia.  20,  Two  sets  of  intercostal  vessels  and  nerves.  Their 
position  with  reference  to  each  other  is  from  above  downward  vein,  artery,  and  nerve.  21,  Great 
splanchnic  nerve.  23,  Vertical  lumbar  vein  and  its  tributaries.  Notice  that  it  is  continued 
directly  into  the  azygos  major.     24,  Another  lumbar  artery.     25,  Lumbar  plexus. 


F'8-  75*  The  Diaphragm  from  Below. — i.  Right  leaflet  of  tendon  of  diaphragm.  2.  Open- 
ing of  the  inferior  vena  cava.  3.  (Esophageal  opening.  (Containing  the  oesophagus.)  4,  Middle 
leaflet  of  the  tendon  of  the  diaphragm.  5,  The  aortic  opening,  with  the  aorta  in  position.  6,  Left 
leaflet  of  tendon  of  diaphragm.     7,  Left  inferior  phrenic  artery.  8,  Right  inferior  phrenic  artery. 


350  A  MANUAL  OF  ANA  TOMY. 

receives  the  six   left,  lower  intercostal  veins,  the  left  medi- 
astinal, and  oesophageal  veins  (lower). 

(3)  The  left  supcrioj'  azygos — azygos  tertius  (often  ab- 
sent). When  present,  receives  the  fourth  to  the  seventh 
or  eighth  intercostal  veins  inclusive,  some  mediastinal,  and 
the  left  bronchial  veins.  It  communicates  with  the  left 
superior  intercostal  vein  above,  and  empties  into  the  azygos 
major  below. 

(4)  The  right  superior  intercostal  vein  is  formed  by  the 
second,  third,  and  sometimes  fourth  right  intercostal  veins, 
and  empties  into  the  azygos  major  as  it  arches  to  terminate 
in  the  vena  cava  superior. 

The  first  right  intercostal  vein  empties  into  the  innomi- 
nate or  vertebral  vein. 

(5)  The  left  superior  i?itercostal,  formed  by  the  first  two 
or  three  left  intercostal  veins,  opens  into  the  innominate 
(left).  It  communicates  below  with  the  left  superior 
azygos. 

The  Intercostal  Nerves.      Fig.  74. 

These  are  the  anterior  branches  of  the  twelve  dorsal 
nerves  which  supply  the  walls  of  the  chest  and  abdomen. 
The  first  intercostal  nerve  sends  four-fifths  of  its  fibres  to 
join  the  brachial  plexus  and  the  remaining  fifth  takes  a 
course  similar  to  the  other  intercostal  nerves. 

The  intercostal  nerves  from  the  second  to  the  sixth  in- 
clusive terminate  anteriorly  as  the  anterior  cutaneous  nerves 
of  the  thorax.  See  page  266.  The  next  nerves  below, 
from  the  seventh  to  the  eleventh  inclusive,  course  between 
the  transversalis  and  internal  oblique  muscles,  and  termi- 
nate in  front  as  the  anterior  cutaneous  nerves  of  the  abdo- 
men. The  course  of  the  twelfth  is  given  with  the  lumbar 
plexus.       All    these    nerves    give    off    lateral     cutaneous 


THE  THORAX.  351 

branches  (excepting  the  first),  which  pierce  the  overlying 
muscles  and  supply  the  side  of  the  body  from  the  axilla  to 
the  crest  of  the  ilium.  Each  lateral  cutaneous  nerve 
divides  into  an  anterior  and  posterior  branch  in  passing  to 
its  distribution.  In  addition  to  this  the  lateral  cutaneous 
branch  of  the  second  nerve  passes  to  supply  the  posterior 
upper  part  of  the  arm,  and  is  called  the  intercostohumeral 
nerve.      See  page  280. 

The  Diaphragm.      Figs.  71,  75. 

Origin. — From  the  posterior  surface  of  the  ensiform  ap- 
pendix, from  the  inner  surface  of  the  cartilages  of  the  six 
lower  ribs,  from  the  ligamentum  arcuatum  externum 
and  internum,  and  by  two  crura  from  the  anterior  surface 
and  intervertebral  discs  and  anterior  common  ligament  of 
the  first  to  the  fourth  lumbar  vertebrae  (on  the  right  side), 
and  from  the  first  to  the  second  or  third  (on  the  left  side). 

Insertion. — Into  the  central  tendon,  which  presents  three 
portions  or  leaves,  two  lateral  and  one  central. 

Nerve  Supply. — The  phrenics,  bringing  filaments  from  the 
third,  fourth,  and  fifth  cer\'ical  nerves.  These  nerves  pass 
through  the  muscle  and  are  distributed  to  its  under  surface. 

Action. — To  produce  inspiration  by  lengthening  the  verti- 
cal dimension  of  the  thorax.  To  compress  the  viscera  and 
aid  in  all  expulsive  efforts,  as  defsecation,  micturition,  par- 
turition, and  vomiting.  In  vomiting  the  diaphragm  con- 
tracts to  form  a  hard  surface  against  which  the  stomach 
is  compressed  by  the  action  of  the  abdominal  muscles. 

Opening's  Through  the  Diaphragm. 

Aortic  opening  lies  immediately  in  front  of  the  spine.  It 
gives  passage  to  the  aorta,  vena  azygos  major,  and  thoracic 
duct. 

The  (xsopliageal  opening  lies  in  front  of  the  aortic  to  the 


352  A  MANUAL   OF  ANATOMY. 

left  of  the  middle  plane  of  the  body.  The  oesophagus  with 
the  pneumogastric  nerves  pass  through  it.  Also  some 
small  oesophageal  arterial  filaments. 

The  caval  opening  is  in  the  right  portion  of  the  diaphragm 
at  the  posterior  border  of  the  central  tendon  where  the 
right  and  middle  leaflets  join.  Through  it  passes  the  inferior 
vena  cava. 

Through  the  crura  pass  the  cord  of  the  sympathetic 
nerve,  the  splanchnic  nerves,  and  in  addition,  on  the  left 
side,  the  azygos  minor  vein. 

Having  removed  the  heart  and  great  vessels  (viz.  :  the 
ascending  and  transverse  aorta  and  its  branches,  the  pul- 
monary artery,  the  superior  cava),  the  trachea  and  lungs,  in 
one  mass,  they  are  to  be  dissected  : — 

(i)  The  heart,  great  vessels,  coronary  arteries,  ventricles, 
and  auricles  are  to  be  studied  as  they  are  seen  from  the 
front.  (2)  The  structures  and  their  relations  which  com- 
pose the  root  of  the  lungs  are  to  be  investigated.  (3)  Sep- 
arate the  heart  (and  vessels)  from  the  lungs  (and  trachea). 
(4)  Complete  the  dissection  of  the  posterior  of  the  heart 
(ventricles,  auricles,  and  vessels),  then  open  its  cavities  and 
learn  their  parts  or  contents.  (5)  Complete  the  study  and 
comparison  of  the  right  and  left  lung,  inflating  them  for 
this  purpose.  (6)  Follow  up  the  bronchi  to  the  main  sub- 
divisions, three  for  the  left  and  two  for  the  right  lung. 

The  Right  Coronary  Artery.     Figs.  70,  7 1 . 

Comes  off  from  the  anterior  sinus  of  Valsalva  of  the 
aorta,  appears  between  the  right  auricle  and  pulmonary 
artery,  follows  the  auriculoventricular  groove  to  the  right 
border  of  the  heart,  here  divides  into  two  terminal  arteries. 
One  continues  the  course  around  in  the  auriculoventri- 
cular groove  to  the  back  of  the  heart  to  anastomose  with  a 


THE  THORAX.  353 

similar  one  from  the  left  coronary  artery.  The  other,  the 
interventricular,  descends  in  the  posterior  (right)  interven- 
tricular groove  to  the  apex  of  the  heart  to  enter  into  an 
anastomosis  with  the  left  artery.  The  right  artery  also 
gives  off  several  other  branches  to  the  front  and  side  of  the 
heart  (right  auricle). 

The  Left  Coronary  Artery.      Figs.  70,  71,  72. 

Is  given  off  from  the  left  (posterior)  sinus  of  Valsalva, 
issues  between  the  left  auricle  and  the  pulmonary  artery, 
curves  downward  in  the  left  interventricular  groove  to  the 
apex  of  the  heart  to  form  a  free  anastomosis  with  the  right 
artery.  It  gives  off  a  branch  which  turns  backward  in  the 
auriculoventricular  groove  to  anastomose  with  the  similar 
branch  of  the  right.  Both  arteries  supply  the  auricles  and 
beginning  of  the  great  vessels. 

The  Cardiac  Veins.     Figs.  70,  71,  72,  73. 

They  take  up  the  blood  from  the  area  of  the  heart  sup- 
plied by  the  above  arteries,  which  they  accompany. 

The  coronary  sinus  extends  from  the  anterior  interventri- 
cular vein  (of  which  it  is  a  continuation)  around  the  left 
margin  of  the  heart  to  the  right  auricle.  Near  the  auricle 
it  receives  the  right  (posterior)  interventricular  vein. 

The  anterior  intcrvcntriailar  (great  cardiac)  vein  follows 
upward  in  the  sulcus  with  the  left  artery,  it  reaches  the 
auriculoventricular  groove,  turns  backward  in  it  to  the  right 
auricle,  into  which  it  empties.  The  portion  of  the  vein  in 
the  auriculoventricular  groove  is  called  the  coronary  sinus  ; 
it  is  about  an  inch  long,  and  receives  the  oblique  vein  of 
Marshall,  posterior  cardiac  veins,  and  the  posterior  inter- 
ventricular vein  (accompanies  the  right  coronary  arter}'), 
the  last  just  before  it  enters  the  auricle. 
23 


354  A  MANUAL  OF  ANA  TOMY. 

The  Cardiac  Nerves. 

The  cardiac  nerves  are  supplied  from  the  pneumogastric, 
recurrent  laryngeal  nerves,  and  the  three  cervical  gangHa. 

The  minute  filaments  from  these  sources  interlace  in  the 
concavity  of  the  aortic  arch,  in  front  of  the  right  pulmonary 
artery  (forming  the  superficial  cardiac  plexus),  and  be- 
hind the  transverse  aorta,  between  the  trachea  and  the 
transverse  aorta  (forming  the  deep  cardiac  plexus). 

The  deep  plexus  receives  branches  from  all  the  sources 
above,  except  from  the  left  superior  sympathetic  cardiac 
and  the  left  inferior  cardiac  of  the  pneumogastric.  The 
superficial  plexus  is  formed  by  the  two  exceptions  above 
and  by  the  branches  from  the  deep  plexus  itself 

From  these  plexuses  branches  descend  to  the  heart  and 
lungs. 

Inferior  Vena  Cava. 

For  formation  and  course  see  Abdomen. 

It  enters  the  thorax  from  the  abdomen  through  the  caval 
opening  in  the  diaphragm  to  the  right  of  the  thoracic  aorta, 
and  in  front  of  the  dorsal  vertebrae,  and  empties  into  the 
right  auricle  of  the  heart.  It  is  covered  by  pericardium  for 
about  one-half  inch. 

The  Heart.     (See  page  330.)     Figs.  70  to  73. 

Note  its  shape,  size,  position  of  parts,  and  their  relations 
to  each  other.      For  the  external  relations  see  page  258. 

Open  the  ventricles  by  incisions  from  the  pulmonary 
artery  and  the  aorta  to  the  apex  through  the  right  and  left 
sides  of  the  heart.  Open  the  auricles  by  incisions  parallel 
with  the  auriculoventricular  groove. 

The  Right  Auricle. — Openings,  superior  vena  cava,  in- 
ferior vena  cava,  auriculoventricular,  coronary  sinus,  fora- 
mina Thebesii. 


THE  THORAX.  355 

The  opening  of  the  coronary  sinus  is  found  between  that 
of  the  inferior  vena  cava  and  the  auriculoventricular.  It  is 
guarded  by  the  valve  of  Thchesiiis,  formed  by  a  redupHca- 
tion  of  the  endocardium. 

The  inferior  caval  opening  is  protected  by  the  Etistacliian 
valve. 

The  Uibcrcle  of  Lower  is  found  between  the  two  caval 
openings  and  at  their  right. 

The  appendix  and  anterior  surface  of  the  auricle  is  thrown 
into  ridges  by  the  inusculi  pectinati. 

The  septum  between  the  two  auricles  is  depressed,  form- 
ing the  fossa  ovalis  (in  the  foetus  it  is  an  opening),  sur- 
rounded by  a  border,  the  annuhis  ovalis. 

The  Left  Auricle. — Openings.  Four  pulmonary  veins 
(two  may  open  by  one  orifice),  auriculoventricular,  fora- 
mina Thebesii. 

The  nmsculi  pectinati  are  found  in  the  appendix. 

The  Right  Ventricle. — Openings.  The  auriculoventri- 
cular from  the  auricle,  the  pulmonary  artery.  The  former 
is  guarded  by  the  tricuspid  valves,  the  latter  by  the  semi- 
lunar. 

The  tricuspid  valve  is  formed  of  three  main  and  three 
secondary  triangular  flaps  of  membrane.  These  flaps  or 
cusps  are  attached  by  their  bases  to  the  fibrous  ring  about 
the  auriculoventricular  orifice,  and  also  to  each  other  for  a 
short  distance  from  their  bases. 

The  semilunar  valves,  three  in  number,  situated  at  the 
beginning  of  the  pulmonary  artery  (and  aorta,  also).  They 
are  reduplicated  folds  of  the  inner  coat  of  the  vessel  plus 
some  fibrous  tissue.  At  the  centre  of  the  free  margin  is  a 
small  nodule,  the  corpus  Arantii.  By  the  peculiar  arrange- 
ment of  the  fibrous  tissue  in  the  semilunar  valves  a  huiated 
space  is  left  on  either  side  of  each  corpus  Arantii,  consisting 


356  A  MANUAL  OF  ANATOMY. 

only  of  the  two  layers  of  the  endothelium  of  the  vessel. 
These  thin  places  admit  of  a  closer  apposition  of  the  valves. 

The  sinuses  of  Valsalva  are  hollows  behind  each  cusp 
of  the  semilunar  valves  (whether  in  pulmonary  artery  or  the 
aorta). 

The  sinuses  are  arranged  in  the  pulmonary  artery  with 
two  in  front  (the  left  is  slightly  in  front  of  the  right)  and 
one  in  the  rear. 

In  the  aorta  these  sinuses  are  arranged  with  one  in  front 
and  two  behind.     See  Coronary  Arteries,  pages  352  and  353. 

The  inner  surface  of  the  ventricle  is  corrugated  by  mus- 
cular ridges,  the  columnae  carnese.  These  are  found  in 
three  forms  :  one,  attached  by  their  whole  lengths  ;  a  second, 
by  both  ends  ;  a  third,  by  one  end  (musculi  papillares), 
the  other  end  being  free  and  affording  attachment  to  the 
chordae  tendinese.  The  chordae  tendineae  are  fibrous 
strings  passing  from  the  musculi  papillares  to  the  under 
surface  and  free  borders  of  the  primary  and  secondary  por- 
tions of  the  tricuspid  (and  bicuspid)  valve. 

The  Left  Ventricle. — This  ventricle  is  about  three  times 
thicker  than  the  right  one.  From  it  extends  the  aorta,  and 
into  it  empties  the  left  auricle  through  the  auriculoventri- 
cular  opening.  The  aortic  opening  is  provided  with  semi- 
lunar valves  and  the  auriculoventricular  with  the  bicuspid 
(mitral)  valve,  similar  in  every  way  to  the  semilunar  and 
tricuspid  of  the  right  ventricle. 

The  auriculoventricular  or  bicuspid  valve  is  com- 
posed of  two  main  and  two  secondary  flaps.  Behind  the 
semilunar  valves  the  aortic  wall  is  pouched  ;  these  pouches 
are  called  the  sinuses  of  Valsalva,  as  above  described. 

The  Trachea.      Figs.  18,  70,  71,  72.      Diags.  20,  21. 
The  trachea  is  a  fibromuscular  tube  that  is  prevented 


THE  THORAX.  357 

from  collapsing  like  the  oesophagus  by  the  introduction  of 
incomplete  rings  of  cartilage. 

These  cartilaginous  arches  are  incorporated  within  the 
structure  of  the  tube.  Their  opening  is  placed  behind,  and 
the  gap  filled  in  with  muscular  tissue.  The  trachea  is  the 
continuation  of  the  air  tube  below  the  larynx,  or  the  cricoid 
cartilage.  It  terminates  at  its  bifurcation  into  the  two 
bronchi  at  the  fourth  or  fifth  thoracic  vertebra.  Its  length 
is  about  five  inches  and  its  diameter  nearly  an  inch. 

Relations. — In  the  neck  :  In  front,  skin,  fasciae,  anterior 
jugular  veins,  their  communicating  and  the  inferior  thyroid 
veins,  the  isthmus  of  the  thyroid  gland,  branches  of  the 
superior  thyroid  artery.  Laterally  (and  in  front),  sterno- 
hyoid, sternothyroid  muscles,  lobes  of  the  thyroid  gland. 
Laterally,  lobes  of  the  thyroid  gland  carotid  sheath  and  its 
contents.  Behind,  oesophagus  (and  at  sides,  recurrent 
laryngeal  nerves  and  the  inferior  thyroid  arteries). 

In  the  chest :  In  front,  origin  of  muscles  as  above.  Re- 
mains of  the  thymus  gland.  Left  innominate  vein,  trans- 
verse aorta,  and  the  diverging  innominate  and  left  common 
carotid  arteries,  the  deep  cardiac  plexus.  Laterally,  the 
lungs  and  their  pleurae,  the  pneumogastric  nerves,  and  on 
the  left  side  the  recurrent  laryngeal  nerve.  Behind,  the 
oesophagus. 

The  blood  supply  is  from  the  inferior  thyroid  arteries,  the 
nerve  supply  from  the  pneumogastrics,  recurrent  laryngeals, 
and  sympathetic  nerves. 

The  Bronchi.      Fig.  73.      Diag.  22. 

These  are  constructed  the  same  as  the  trachea,  of  which 
they  are  the  terminal  branches. 

The  bifurcation  of  the  trachea  is  not  at  the  middle  plane 
of  the  trachea,  but  more  to  the  left  side,  consequently  the 


358  A  MANUAL  OF  ANATOAIY. 

right  bronchus  presents  a  more  conspicuous  opening  than 
the  left,  and  therefore  is  more  liable  to  receive  any  object 
inspired  into  the  trachea. 

The  right  bronchus  gives  off  a  large  branch  to  the  upper 
lobe  of  the  lung  and  then  bifurcates  to  supply  the  middle 
and  lower  lobes. 

The  left  bronchus  divides  into  two  branches,  one  for  each 
lobe. 

The  right  bronchus  is  shorter,  wider,  and  more  hori- 
zontal than  the  left.  Its  length  is  about  an  inch  and  its 
width  a  little  more  than  half  as  much.  The  right  pul- 
monary artery  is  below  and  then  in  front  of  the  bronchus. 
The  azygos  major  vein  arches  upward  over  the  bronchus 
from  behind  to  empty  into  the  vena  cava  superior. 

The  left  bronchus  is  longer,  narrower,  and  more  oblique 
than  the  right.  Its  length  is  about  two  inches.  In  front 
of  it  is  the  aortic  arch,  the  left  pulmonary  artery  is  above 
and  then  in  front  of  it.  Behind  the  bronchus  is  the 
oesophagus,  thoracic  duct,  and  descending  aorta. 

The  Lungs.      Figs.  59,  68. 

The  lungs  are  two  in  number,  the  right  and  left.  The 
right  consists  of  three  lobes  and  the  left  of  two. 

When  the  chest  is  intact  they  fill  the  pleural  cavities, 
with  the  exception  of  the  extreme  lower  angle  between  the 
chest  and  diaphragm.  See  page  263.  The  lung  is  de- 
scribed as  having  an  apex,  projecting  into  the  root  of  the 
neck  through  the  upper  opening  of  the  chest,  and  rising 
above  the  first  rib  about  one  and  one-half  inches  (three- 
fourths  of  an  inch  above  the  clavicle)  ;  a  base,  concave,  to 
fit  over  the  convexity  of  the  diaphragm,  upon  which  it 
rests  ;  an  outer  convex  surface  opposed  to  the  interior  of 
the  chest ;  an  inner  surface,  concave,  fitting  over  the  peri- 


THE  THORAX.  359 

cardium  and  heart  and  mediastinum  ;  a  root,  at  which 
point  the  visceral  and  parietal  pleurae  become  continuous, 
and  where  the  bronchial  tube,  vessels,  nerves,  and  lymphatics; 
pass  to  (or  from)  the  lungs  ;  an  anterior  border,  thin, 
notched  on  the  left  side  for  the  heart  (for  its  relation  to 
the  anterior  of  the  chest  see  page  263) ;  a  posterior  border, 
thick,  rounded,  lying  alongside  of  the  spinal  column  ;  and  a 
lower  border,  which  resembles  the  anterior.  For  its  rela- 
tions to  the  chest  wall,  see  page  262. 

The  main  fissure  which  divides  each  lung  into  two  lobes 
passes  from  the  posterior  border,  three  inches  from  the 
apex,  downward  around  the  outer  surface  of  the  lung  to 
end  at  the  lower  portion  of  the  anterior  border. 

Besides  this  main  fissure  the  right  lung  has  a  secondary 
one  that  passes  from  the  centre  of  the  main  fissure  to  the 
anterior  border,  dividing  the  upper  lobe  into  two  portions. 

The  structures  constituting-  the  root  of  the  lung- 
(Fig.  73),  are  the  bronchus,  pulmonary  artery  and  vein, 
the  bronchial  vessels,  nerves,  lymphatic  glands,  the  con- 
necting tissue,  and  all  surrounded  by  the  pleura. 

The  relations  of  the  pulmonary  artery,  vein,  and  bronchus 
are  from  before  backward,  bronchus,  artery,  and  vein. 
On  the  right  side,  from  above  downward,  the  relation  is 
the  same,  but  on  the  left  side  it  is  arter>^  bronchus,  and 
vein. 

The  lungs  weigh  about  forty-two  ounces,  the  right  being 
a  little  heavier  than  the  left. 

Relations  of  the  Roots  of  the  Lungs. — Figs.  71,  72.  Diag. 
22.  The  right  :  In  front,  the  phrenic  nerve,  anterior 
pulmonary  plexus,  superior  vena  cava,  the  right  auricle 
of  the  heart ;  above,  the  azygos  major  ;  below,  broad 
ligament  of  the  lung  ;  and  behind,  the  pneumogastric 
nerve  and  the  posterior  pulmonary  plexus. 


360  A  MANUAL   OF  ANATOMY. 

The  left :  In  front,  phrenic  nerve  and  anterior  pulmonar)^ 
plexus  ;  above,  the  arch  of  the  aorta  ;  below,  same  as  right ; 
behind,  descending  aorta,  pneumogastric  nerve,  and  poste- 
rior pulmonary  plexus. 


UPPER  EXTREMITY  AND  THORAX,  Posterior. 

DISSECTION. 
Incisions. — (i)   From  the  base  of  the  skull  (made  by  the  one  on  the  head 
and  neck)  in  the  median  line  along  the  back  of  the  thorax  (made  by  the  one 
on  the  upper  extremity),  to  tenninate  at  the   tip   of  the  coccyx  (extended  by 
the  one  dissecting  the  lower  extremity) . 

(2)  From  the  median  incision  out  along  the  spine  of  the  scapula  (same  for 
head  and  neck,  page  128)  to  meet  the  similar  incision  in  front  over  the  point 
of  the  shoulder. 

(3)  Carry  a  transverse  cut  from  twelfth  dorsal  spine  around  the  body  to 
meet  the  similar  one  from  the  front. 

This  incision  answers  for  both  upper  and  lower  extremities.  Reflect 
the  integument  from  the  back  of  the  neck,  thorax,  and  trunk ;  from 
the  arm  to  below  the  elbow.  To  expose  the  last  no  farther  incisions  in  the 
skin  are  necessary ;  simply  reflect  it,  beginning  at  the  point  where  its  anterior 
dissection  stopped,  and  working  from  the  outer  to  the  inner  side  of  the  limb. 

This  method  will  also  hold  for  the  removal  of  the  integument  from  the 
back  of  the  forearm,  hand,  and  fingers. 

The  Superficial  Fascia. 

The  superficial  fascia  covering  the  back  of  the  body  from 
the  base  of  the  skull  to  the  end  of  the  spine  is  a  dense, 
brawny  layer  composed  of  connective  and  granular  fatty 
tissue.  In  the  subject  it  is  often  found  infiltrated  by  gravi- 
tated fluid. 

The  superficial  fascia  is  continuous  with  the  similar  layer 
of  other  adjacent  parts  of  the  body.  It  should  be  removed 
in  the  same  manner  as  the  integument.  In  its  removal  an 
outlook  should  be  kept  for  the  superficial  nerves  and 
vessels.     The  cutaneous  nerves  are  the  posterior  divisions 


?      3 


Fig.  76.  Dissection  of  the  Back.— i,  Lisjamentum  iiuchse.  2,  Third  occipital 
nerve.  (Internal  cutaneous  branch  of  the  third  cervical  nerve.)  ?,,  Great  occipital  nerve. 
4,  Trachelomastoid  muscle.  5,  5,  Complexus.  6,  Posterior  part  of  sternomastoid.  7, 
Transversalis  cervicis.  8,  Cervicalis  ascendens.  9,  Scalenus  posticus.  10,  Serratus  pos- 
ticus superior.  11,  Posterior  scapular  artery.  12,  Longissimus  dorsi.  13,  Accessorius  ad 
iliocostalem  or  ad  sacrolumbalem.  14,  Erector  spinae.  15.  Splenius  capitis.  16,  Rhom- 
boideus  minor.  17,  Rhomboideus  major.  18,  Levator  anguli  scapulae.  19,  Supraspinatus. 
20,  Spine  of  scapula.  21,  Clavicle.  22,  Acromion  process.  23,  Teres  minor.  24.  Outer 
head  of  triceps.  25,  Long  head  of  triceps.  26,  Tendon  of  latissimus  dorsi.  27,  Teres 
major.    28,  Serratus  posticus  inferior.    29.  The  vertebral  aponeurosis. 


362  A  MANUAL   OF  ANATOMY. 

of  the  lateral  cutaneous  branches  of  the  intercostal  nerves- 
at  the  side,  and  the  dorsal  branches  from  the  same  source 
along  the  spine.  The  arteries  are  minute  branches  from 
the  intercostals  and  the  other  vessels  which  will  appear 
later. 

The  Deep  Fascia. 

This  is  a  well-marked  layer  of  dense  connective  tissue 
which  covers  in  all  the  structures  of  the  back.  Above,  it 
is  attached  to  the  base  of  the  occipital  bone  along  the  supe- 
rior curved  line,  and  to  the  mastoid  process  of  the  temporal 
bone  ;  laterally,  in  the  neck,  it  becomes  the  outer  layer  of 
the  deep  cervical  fascia,  and  is  attached  to  the  transverse 
processes  of  the  cervical  vertebrae  ;  in  the  middle  line  it  is 
attached  to  the  spinous  process  of  all  the  vertebrae  from  the 
skull  to  the  coccyx,  in  the  neck  forming  the  ligamentum 
nuchae  ;  back  of  the  shoulder  it  is  attached  to  the  spine 
and  acromion  process  of  the  scapula,  and  becomes  continu- 
ous with  the  fascia  covering  the  deltoid  ;  lower  down  it 
covers  in  the  latissimus  dorsi  muscle,  and  at  its  anterior 
border  becomes  continuous  with  the  axillary  fascia  (see 
page  268) ;  below  it  is  attached  to  the  crest  of  the  ilium, 
and  above  the  bone  reaches  around  the  body,  covering  in 
the  external  oblique  muscle. 

DISSECTION. 
Remove  the  deep  fascia,  exposing  the  first  layer  of  muscles. 

The  Trapezius.      Fig.  yy. 

Origin. — From  the  inner  third  of  the  superior  curved 
line  of  the  occipital  bone  and  occipital  protuberance,  from 
all  the  spines  of  the  cervical  vertebrae  by  means  of  the  liga- 
mentum nuchas,  from  the  spines  of  all  the  dorsal  vertebras 
and  the  supraspinous  ligament. 


UPPER  EXTREMITY  AND  THORAX,  POSTERIOR.      363 

Insertion. — Into  the  posterior  portion  of  the  upper  surface 
and  border  of  the  outer  third  of  the  clavicle  ;  into  the  upper 
border  of  the  spine  and  acromion  process  and  the  slight 
tubercle  near  the  base  of  the  spine  of  the  scapula. 

Nerve  Supply. — The  spinal  accessory  and  deep  branches 
of  the  third  and  fourth  cervical  nerves.  They  are  distrib- 
uted to  the  anterior  surface  of  the  muscle. 

Action. — The  spine  and  head  being  the  fixed  points  and 
both  muscles  acting,  the  shoulders  will  be  drawn  backward 
and  the  points  of  the  shoulders  slightly  deviated.  The 
muscles  acting  singly  and  in  parts  from  the  fixed  spine  :  if 
the  upper  portion  acts,  the  clavicle  and  acromion  will  be 
raised  (shoulder  elevated)  ;  if  the  middle  portion  of  the 
muscle  acts,  the  scapula  will  be  drawn  toward  the  spine,  a 
slight  rotation  taking  place  at  the  same  time  ;  if  the  lower 
portion  acts,  the  vertebral  border  of  the  spine  will  be  drawn 
downward  (the  shoulder  carried  downward  and  backward), 
at  the  same  time  the  point  of  the  shoulder  is  very  slightly 
elevated.  Acting  from  the  shoulder  as  the  fixed  point, 
both  muscles  will  retract  the  head  and  neck  and  elevate  the 
chin  ;  one  muscle  acting,  will  carry  the  chin  to  the  opposite 
side  and  flex  the  neck  laterally. 

The  muscle  fixing  the  shoulders  gives  the  accessory 
muscles  of  inspiration  a  better  chance  for  acting. 

The  Deltoid.      Fig.  60. 

Origin. — From  the  anterior  border  of  the  outer  third  of 
the  clavicle,  from  the  outer  margin  of  the  acromion, 
lower  lip  of  the  spine  of  the  scapula,  and  the  infraspinatus 
fascia. 

Insertion. — For  a  distance  of  two  or  three  inches  into 
the  outer  surface  of  the  humerus  just  above  its  middle,  at 
a  rough  triangular  surface. 


364  A  MANUAL   OF  ANA  TOMY. 

Nerve  SiLpply. — The  circumflex,  which  furnishes  fibres 
from  the  fifth  and  sixth  cervical  nerves. 

Action. — To  abduct  the  arm  to  a  right  angle  with  the 
body.  The  anterior  portion  of  the  muscle  will  flex  and  ad- 
duct  the  arm  to  (less  than)  a  right  angle,  while  the  poste- 
rior portion  will  adduct  and  extend  the  arm  to  half  a  right 
angle. 

The  elevation  of  the  arm  beyond  a  right  angle  is  ac- 
complished through  the  action  of  the  trapezius  and  serratus 
magnus  muscles  by  producing  a  rotation  of  the  scapula 
and  elevation  of  the  outer  end.  The  clavicle  moves  up- 
ward and  at  the  same  time  rotates  upon  its  long  axis. 

The  deltoid  really  is  a  continuation  of  the  direction  of 
the  fibres  of  the  trapezius  and  so  extends  its  action. 

DISSECTION. 
Cut  the  trapezius  away  from  its  insertion,  divide  the  nerves  passing  to  it, 
and  roll  the  muscle  up  to  the  spine. 

Complete  the  cleaning  of  the  latissimus  dorsi  muscle. 

The  Latissimus  Dorsi. 

Origin. — From  the  spines  and  supraspinous  Hgaments  of 
the  lower  six  dorsal  and  all  the  lumbar  vertebrae,  and 
through  the  lumbar  aponeurosis,  from  the  spines  of  the 
sacral  vertebrae  and  the  outer  lip  of  the  posterior  third  of 
the  crest  of  the  ilium,  from  the  outer  surface  of  the  three 
or  four  lower  ribs  external  to  their  angles,  and  from  the 
outer  surface  of  the  lower  angle  of  the  scapula. 

Insertion. — Into  the  bottom  of  the  bicipital  groove  of 
the  humerus. 

Nerve  Supply. — The  long  or  second  subscapular  nerve. 
The  filaments  coming  from  the  fifth  cervical  nerve. 

Action. — The  origin  being  the  fixed  point,  the  muscle  acts 
to  draw  the  humerus  (and  shoulder)  downward,  backward, 


UPPER  EXTREMITY  AXD  THORAX,  POSTERIOR.      365 

and  inward,  and  to  rotate  the  humerus  inward  (adduction, 
extension,  and  internal  rotation  of  humerus). 

The  insertion  being  the  fixed  point,  the  muscle  will  raise 
the  body  and  swing  it  forward  (if  both  muscles  are  acting) 
or  to  one  side  (if  only  one  muscle  acts).  Acting  upon  the 
ribs,  it  will  raise  them  and  act  as  an  accessory  muscle  of 
inspiration. 

DISSECTION. 

Cut  the  deltoid  away  from  its  origin  and  turn  it  downward  and  forward  ;  in 
doing  so  save  its  nerve  and  arterial  supply. 

Disarticulate  the  clavicle  from  its  acromial  attachment ;  divide  the  coraco- 
clavicular  ligaments  and  draw  the  clavicle  out  of  the  way. 

Remove  the  supra-  and  infraclavicular  fasciae  and  clean  the  muscles  covered 
by  them.  Also,  clean  the  levator  anguli  scapulas,  rhomboid,  and  teres 
muscles.     Remove  the  fascia  covering  the  triceps. 

The  superficial  fascia  of  the  arm  has  been  already  de- 
scribed (see  page  282). 

The  cutaneous  nerves  of  the  back  of  the  shoulder  and 
arm. 

The  shoulder  receives  filaments  through  the  acromial 
nerves  from  the  third  and  fourth  cervical  nerves.  See  page 
91. 

The  deltoid  region  of  the  arm  and  a  small  surface  of  the 
outer  part  of  the  arm  from  the  deltoid  half-way  to  the  elbow 
is  supplied  by  the  circumflex  nerve. 

The  rest  of  the  outer  portion  of  the  arm  is  supplied  by 
the  superior  external  cutaneous  branch  of  the  musculo- 
spiral  nerve. 

The  inner  half  of  the  back  of  the  arm  is  supplied  from 
above  downw^ard  by  the  iiiternal  cutaneous  branch  of  the 
musculospiral,  the  intercostohumeral,  and  the  lesser  internal 
cutaneous  nerves. 


366  A  MANUAL  OF  ANA  TOMY. 

The  Levator  Anguli  Scapulae.      Fig.  'j6. 

Oj'igin. — From  the  posterior  tubercles  of  the  transverse 
processes  of  the  three  or  four  upper  cervical  vertebrae. 

Insertion. — Into  the  upper  fourth  of  the  vertebral  border 
of  the  scapula. 

Nerve  Supply. — The  third  and  fourth  cervical  nerves. 

Action. — To  raise  the  inner  portion  of  the  scapula,  at  the 
same  time  depressing  the  shoulder. 

The  Rhomboideus  Major  and  Minor.      Fig.  y6. 

These  muscles  will  be  described  together,  as  they  are 
really  one. 

Origin. — From  the  lower  portion  of  the  ligamentum 
nuchae,  the  spinous  processes  of  the  last  cervical  and  the 
four  or  five  upper  dorsal  vertebrae,  and  the  supraspinous 
ligament. 

Insertion. — Into  the  lov/er  three-fourths  of  the  vertebral 
border  of  the  scapula. 

Nerve  Supply. — Branches  from  the  fifth  cervical  nerve. 

Action. — To  draw  the  scapula  to  the  spine  and  at  the 
same  time  elevate  the  inner  border  ;  this  also  depresses  the 
outer  portion  of  the  bone  (and  the  shoulder). 

The  Supraspinatus.      Fig.  76. 

Origin. — From  the  inner  two-thirds  of  the  supraspinous 
fossa  and  the  inner  surface  of  the  supraspinous  fascia. 

Insertion. — Into  the  upper  facet  upon  the  greater  tuber- 
osity of  the  humerus.  Its  under  fibres  are  also  continued 
into  the  capsular  ligament  of  the  shoulder-joint. 

Nerve  Supply. — From  the  fifth  cervical  nerve  through  the 
suprascapular. 

Action. — To  abduct  the  humerus,  but  more  especially  to 
hold  the  head  of  the  humerus  against  the  glenoid  cavity 
of  the  scapula. 


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368  A  MANUAL  OF  ANATOMY. 

The  Infraspinatus.     Fig.  ^6. 

Origin. — From  the  under  surface  of  the  spine  of  the 
scapula,  from  the  inner  two-thirds  of  the  posterior  surface 
of  the  scapula  reaching  from  the  spine  to  the  origin  of  the 
teres  muscles,  and  from  the  inner  surface  of  the  infraspinous 
fascia. 

Insertion. — Into  the  middle  facet  upon  the  greater  tuber- 
osity of  the  humerus,  and  into  the  capsular  ligament  of  the 
shoulder-joint. 

Nerve  Supply. — The  same  as  the  supraspinatus.  See 
above. 

Action. — Primarily  it  is  an  external  rotator  of  the  arm  -, 
if  the  arm  is  extended  and  drawn  forward  the  muscle  will 
adduct  and  extend  it  slightly. 

The  Teres  Minor.      Figs.  ^6,  JJ. 

Origin. — From  the  upper  two-thirds  of  the  posterior 
surface  of  the  axillary  border  of  the  scapula,  and  from  the 
septa  between  it,  the  teres  major,  and  infraspinatus  muscles. 

Insertion. — Into  the  lowest  facet  upon  the  greater  tuber- 
osity, and  into  the  shaft  of  the  bone  for  an  inch  below. 

Nerve  Supply. — The  circumflex.  The  filaments  are  fur- 
nished by  the  fifth  cervical  nerve. 

Action. — An  external  rotator  and  adductor  of  the  arm. 

The  Teres  Major.      Figs.  J^,  J  J. 

Origin. — From  the  lower  third  of  the  posterior  surface  of 
the  axillary  border,  and  from  the  posterior  surface  of  the 
inferior  angle  of  the  scapula,  and  from  the  septa  which  in- 
tervene between  it  and  the  teres  minor  and  the  infraspinatus 
muscles. 

Insertion. — By  a  tendon  nearly  two  inches  broad  into  the 
inner  bicipital  ridge  of  the  humerus. 


UPPER  EXTREMITY  A XD   THORAX,  POSTERIOR.      369 

Nerve  Supply. — The  lowest  or  third  subscapular,  bringing 
filaments  from  the  sixth  and  seventh  cervical  nerves. 

Action. — To  rotate  the  arm  inward  and  adduct  it,  also  to 
draw  the  arm  backward  when  it  has  been  carried  forward. 

The  Triceps.     Fig.  77. 

Origin. — The  long  or  middle  head  rises  from  the  axillary 
border  of  the  scapula  just  below  the  glenoid  cavity  (and 
from  the  lower  portion  of  the  capsule  of  the  shoulder-joint). 

The  external  head  comes  from  the  posterior  surface  of 
the  humerus  above,  and  external  to  the  musculospiral 
groove  (reaching  up  as  high  as  the  insertion  of  the  teres 
minor). 

The  internal  head  from  the  surface  of  the  humerus  below 
and  internal  to  the  same  groove  (reaching  up  to  the  inser- 
tion of  the  teres  major). 

The  external  and  internal  heads  also  arise  from  the  pos- 
terior surface  of  the  external  and  internal  intermuscular 
septa  opposite  their  bony  origins. 

I)iscrtio)i. — Into  the  tip  of  the  olecranon  process  of  the 
ulna,  and  into  the  deep  fascia  of  the  forearm. 

Nerve  Supply. — The  musculospiral.  The  source  of  the 
filaments  is  from  the  seventh  and  eighth  cervical  nerves. 

Ac/ioii. — Primarily,  upon  the  forearm  to  extend  it ; 
secondarily,  upon  the  arm  to  adduct  and  support  it. 

The  Subanconeus. — This  is  not  a  separate  muscle, 
merely  some  fibres  of  the  triceps  which  are  inserted  into 
the  posterior  part  of  the  ligament  of  the  elbow-joint.  Its 
function  is  to  raise  the  ligament  in  extension  of  the  joint 
and  keep  it  out  of  the  way  of  the  bones. 

DISSECTION. 
Find  the  suprascapular  artery  and  nerve,  trace  them  over  the  upper  border 
of  the  scapula.     Divide   the   supraspinatus   muscle  and  follow  the  artery  and 
24 


370  A  MANUAL  OF  ANA  TOMY. 

nerve  through  the  scapular  notch  into  the  infraspinous  fossa,  to  terminate  in 
the  muscle  there. 

Find  the  dorsalis  scapulae  artery  and  trace  its  course  upon  the  back  of  the 
scapula,  cutting  as  much  of  the  overlying  muscle  away  as  is  necessary  to  fol- 
\o^  it. 

In  the  same  way  dissect  out  the  circumflex  nerve  and  the  posterior  circum- 
flex artery  to  their  distribution  to  the  teres  minor  and  deltoid  muscles. 

Divide  the  rhomboid  muscles  vertically  midway  between  their  attachments 
and  reflect  them. 

At  the  upper  part  of  the  vertebral  border  of  the  shoulder  find  the  posterior 
scapular  artery  and  trace  its  branches  as  far  as  possible. 

Cut  the  latissimus  dorsi  transversely  at  its  middle  and  reflect  its  central 
portion,  severing  it  from  its  costal  attachments. 

The  Serratus  Posticus  Superior.      Fig.  76. 

Origin. — From  the  lower  portion  of  the  ligamentum 
nuchae,  the  spines  of  the  last  cervical  and  first  three  dorsal 
vertebrae,  and  the  supraspinous  ligaments. 

Insertion. — Into  the  posterior  surface  of  the  second  to 
the  fifth  ribs  inclusive,  just  external  to  their  angles. 

Nerve  Supply. — The  second  and  third  intercostal  nerves. 

Action. — To  raise  the  ribs  and  aid  in  inspiration. 

The  Serratus  Posticus  Inferior.      Fig.  76. 

Origin. — From  the  spines  of  the  last  two  dorsal  and  first 
two  lumbar  vertebrae. 

Insertion. — Into  the  lower  borders  of  the  last  four  ribs. 

Nej^ve  Supply. — The  tenth  and  eleventh  intercostals. 

Action. — To  draw  the  ribs  downward,  thus  affording  a 
fixed  point  for  the  action  of  the  diaphragm  and  so  aiding 
inspiration. 

The  Posterior  Scapular  Artery.      Fig.  76. 

Usually  arises  from  the  third  portion  of  the  subclavian, 
but  may  come  off  as  the  lower  branch  of  the  transverse 
cervical. 

For  its  course  from  the  subclavian  see  page  113.     When 


UPPER  EXTREMITY  AND   THORAX,  POSTERIOR.      371 

found  at  the  back  it  is  covered  by  the  trapezius,  levator 
anguli  scapuli,  rhomboid  muscles.  Its  course  is  around 
the  upper  angle  and  along  the  vertebral  border  of  the 
scapula  to  its  lower  angle. 

It  anastomoses,  {a)  in  the  supraspinous  fossa,  with  the 
suprascapular  ;  (/^)  in  the  infraspinous  fossa,  with  the  dor- 
salis  scapulae,  and  (r)  at  its  terminus  with  the  subscapular. 

Its  muscular  branches  supply  the  adjacent  muscles. 

The  Suprascapular  Artery  and  Nerve.      Fig.  yj. 

The  artery  is  one  of  the  branches  of  the  thyroid  axis. 
See  page  ii2.      Origin  of  nerve.      See  page  315. 

In  this  part  of  the  dissection  it  is  found  passing  into  the 
supraspinous  fossa  over  the  transverse  ligament  of  the 
scapula,  while  the  suprascapular  nerve  passes  under  it, 
through  the  foramen  which  it  forms  out  of  the  notch  in 
the  scapula. 

The  nerve  and  artery  take  the  same  course  through  the 
supraspinous  fossa  and  great  scapular  notch,  and  terminate 
in  the  infraspinous  fossa.  Both  supply  the  supra-  and  infra- 
spinatus muscles  and  the  shoulder  joint. 

The  artery  anastomoses  with  the  posterior  scapular  in  the 
supraspinous  fossa,  the  dorsalis  scapular  in  the  infraspinous 
fossa,  and  the  acromial  branch  of  the  acromiothoracic  over 
the  spine  and  acromial  process  of  the  scapula. 

The  Dorsalis  Scapulae.     Fig.  jj. 

This  large  branch  from  the  subscapular  (really  the  con- 
tinuation of  the  artery)  appears  at  the  back  in  the  triangular 
interval  between  the  subscapularis  above,  the  teres  major 
below,  and  the  long  tendon  of  the  triceps  at  the  outer  side, 
and  under  cover  of  the  teres  minor,  between  which  and 
the  bone  it  passes  into  the  infraspinous  fossa  to  anastomose 
with  the  suprascapular  and  posterior  scapular  arteries. 


372  A  MANUAL   OF  AAA  TOMY. 

The    Posterior     Circumflex     Artery    and     Circumflex 

Nerve.     Fig.  jy. 

The  artery  is  a  branch  from  the  third  portion  of  the 
axillary,  the  nerve  comes  from  the  posterior  cord  of  the 
brachial  plexus.  See  pages  279  and  318.  They  are  found 
coming  through  a  quadrilateral  space  bounded  above  (and 
in  front)  by  the  subscapularis  (behind  by  the  teres  minor), 
below  by  the  teres  major,  internally  by  the  long  head  of  the 
triceps  muscle,  and  externally  by  the  humerus. 

The  nerve  supplies  the  teres  minor  and  deltoid  muscles 
and  sends  branches  to  the  shoulder-joint  and  the  skin  over 
the  deltoid  and  middle  third  of  outer  surface  of  the  arm. 
The  artery  supplies  these  muscles,  the  joint  of  the  shoulder, 
and  anastomoses  with  the  anterior  circumflex,  and  by  a 
large  branch  with  the  superior  profunda  arteries. 

The  Superior  Profunda  Artery  and  the  Musculospiral 

Nerve.  Fig.  yy . 
These  are  found  together  as  they  course  through  the 
musculospiral  groove,  from  the  inner  to  the  outer  side  of 
the  arm,  where  the  nerve  terminates  by  dividing  into  its 
radial  and  posterior  interosseous  branches  (see  page  318), 
and  the  artery  by  anastomosing  with  the  radial  recurrent. 
The  artery  also  sends  a  branch  upward  to  anastomose 
with  the  posterior  circumflex  and  one  downward — the 
articular — which,  descending  in  the  substance  of  the 
triceps,  supplies  that  muscle,  and  terminates  in  the  anasto- 
motic circle  about  the  elbow-joint  (for  which  see  page  387). 

DISSECTION. 

Divide  the  levator  anguli  scapulae  and  rhomboid  muscles.  Clean  the 
inner  surface  of  the  serratus  magnus,  noting  its  attachments. 

Remove  the  serrati  muscles  and  clean  the  fascia  covering  the  extensor 
muscles  of  the  spine  and  note  its  attachments. 


UPPER  EXTREMITY  A XD  THORAX,  POSTERIOR.      373 

The  Vertebral  Aponeurosis.      Fig.  j^. 

This  aponeurosis  starts  in  the  cervical  region  as  a  very 
thin  layer,  but  gradually  becomes  thicker  as  it  descends, 
until  in  the  lower  dorsal  and  lumbar  regions  it  is  somewhat 
thicker.  In  the  last  region  it  receives  the  tendons  of  the 
latissimus  dorsi  and  serratus  posticus  inferior  muscles.  It 
is  attached  in  the  median  line  to  the  spines  and  supraspi- 
nous ligaments  of  the  vertebrae  extending  from  the  sacrum 
to  the  base  of  the  skull ;  laterally  it  passes  in  the  cervical 
region  to  the  tips  of  the  transverse  processes,  in  the  dorsal 
region  to  the  angles  of  the  ribs,  and  in  the  lumbar  region 
to  the  crest  of  the  ilium,  and  becomes  continuous  with  the 
lumbar  fascia.  From  the  lumbar  portion  of  the  aponeurosis 
arises  the  latissimus  dorsi  and  the  serratus  posticus  inferior 

muscles. 

DISSECTION. 

Remove  the  fascia  and  expose  the  muscles  beneath.  Separate  them  care- 
fully and  make  out  the  limits  of  each. 

Note. — The  person  dissecting  the  lower  extremity  removes  the  fascia 
from  the  lumbar  region,  the  one  on  the  thorax  the  portion  there,  and  the  one 
on  the  head  and  neck  the  cervical  portion. 

The  Extensor  Muscles  of  the  Spine.     Fig.  y6. 

The  spinal  gutter  alongside  of  the  spinous  processes  is 
filled  up  by  a  muscular  mass  extending  from  the  sacrum  to 
the  base  of  the  skull. 

This  muscular  mass,  though  really  continuous  and  con- 
stituting one  muscle,  in  action  is  divided  into  separate  por- 
tions for  convenience  of  reference. 

Below,  the  mass  is  found  blended  together  to  form  the 
erector  spinse,  which  fills  in  the  lumbar  portion  of  the  spinal 
gutter.  Above,  the  continuation  of  the  erector  spinae  is 
represented  by  three  columns.  The  inner  column,  repre- 
sented by  the  spinalis  dorsi ;  the  middle  column,  by  the 
longissimus  dorsi,  transversalis  cervicis,  and   trachelomas- 


374  A  MANUAL   OF  ANA  TOMY. 

toid ;  the  external  column,  by  the  ihocostalis,  accessorius, 
and  cervicalis  ascendens. 

The  Erector  Spinas. 

Origin. — From  the  lowest  two  or  three  dorsal  and  all 
the  lumbar  and  sacral  spines,  from  the  back  of  the  sacrum, 
from  the  posterior  one-fifth  of  the  crest  of  the  ilium  and  the 
posterior  iliac  spines. 

Insertion. — Its  fibres  pass  into  the  spinalis  dorsi  (inner), 
longissimus  dorsi  (middle),  and  iliocostalis,  or  sacrolum- 
balis  (external)  muscles. 

Nerve  Supply. — The  posterior  branches  of  the  lumbar 
nerves. 

Action. — See  below. 

The  Spinalis  Dorsi.      (Inner  column.) 

Origin. — The  inner  portion  of  the  erector  spinae. 

Insertion. — The  spinous  processes  of  the  upper  dorsal 
vertebrae  (four  to  nine). 

Nerve  Siipply. — The  posterior  branches  of  the  dorsal 
nerves. 

Action. — To  extend  the  thoracic  portion  of  the  spine. 

The  Long-issimus  Dorsi.      (Middle  column.) 

Origin. — The  middle  portion  of  the  erector  spinae. 

Insertion. — (Inner  tendons.)  The  transverse  processes 
of  the  dorsal,  and  the  accessory  tubercles  of  the  lumbar 
vertebrae. 

(Outer  set.)  To  the  transverse  processes  of  the  lumbar 
vertebrae,  to  the  lower  ten  ribs  external  to  their  tubercles. 

Nerve  Supply  and  Action. — See  below. 

Transversalis  Cervicis.      (Middle  column.) 

Origin. — From  the  transverse  processes  of  the  upper 
four  or  five  dorsal  vertebrae. 


UPPER  EXTREMITY  AND   THORAX,  POSTERIOR.      375 

Insertion. — Into  the  posterior  tubercles  of  the  transverse 
processes  of  the  cervical  vertebrae  from  the  second  to  the 
sixth  inclusive. 

Nerve  Supply. — External  posterior  branches  of  the  dorsal 
nerves. 

Action. — See  below. 

Trachelomastoid.      (Middle  column.) 

Origin. — From  the  four  or  five  upper  transverse  pro- 
cesses of  the  dorsal  vertebrae,  from  the  articular  processes 
of  the  lower  four  cervical  vertebrae. 

Insertion. — Into  the  posterior  border  of  the  mastoid 
process. 

Nerve  Supply. — The  posterior  branches  of  the  cervical 
nerves. 

Action  of  the  Middle  Column. — To  extend  the  spine  in 
the  cervical,  dorsal,  and  lumbar  regions  ;  to  flex  the  spine 
laterally  ;  to  extend  and  flex  the  head  laterally  and  rotate 
the  chin  to  the  same  side. 

Iliocostalis  (Sacrolumbalis).     (External  column.) 

Origin. — The  outer  portion  of  the  erector  spinae. 

Insertion. — Into  the  angles  of  the  six  lower  ribs. 

Nerve  Supply. — External  posterior  branches  of  the  lum- 
bar nerves. 

Action. — See  below. 

Accessorius.      (External  column.) 

Origin. — From  the  angles  of  the  lower  six  ribs. 

Insertion. — Into  the  angles  of  the  six  upper  ribs  and  the 
transverse  process  of  the  seventh  cervical  vertebra. 

Nerve  Supply. — The  posterior  division  of  the  dorsal 
nerves. 

Action. — See  below. 


376  A  MANUAL   OF  ANATOMY. 

Cervicalis  Ascendens.      (External  column.) 

Origin. — From  the  angles  of  the  five  upper  ribs. 

Insertion. — Into  the  posterior  tubercles  of  the  transverse 
processes  of  the  fourth,  fifth,  and  sixth  cervical  vertebrae. 

Nerve  Supply. — The  external  posterior  branches  of  the 
cervical  nerves. 

Action  of  External  Column. — To  extend  and  flex  later- 
ally the  cervical,  dorsal,  and  lumbar  regions  of  the  spine. 
To  draw  the  ribs  downward  and  act  to  aid  expiration. 

DISSECTION. 

Remove  the  above  muscles  to  expose  the  deeper  layers  which  occupy  the 
space  between  the  spines  and  tips  of  the  vertebrae  and  transverse  processes  of 
the  vertebrse. 

The  muscles  comprising  the  two  last  layers  will  not  be  given  here,  as  their 
study  and  dissection  is  more  theoretical  than  practical. 

The  sixth  layer  is  composed  of  the  complexus  (see  page 
132),  semispinalis  dorsi,  semispinalis  colli,  multifidus  spinse, 
and  rotatores  spinae.  The  seventh  layer  is  formed  of  the 
interspinales  and  the  intertransversales. 

For  the  suboccipital  muscles  see  Head  and  Neck,  page  1 34. 

The  Posterior  Branches  of  the  Spinal  Nerves. 

For  the  cervical  nerves  see  page  129. 

The  dorsal,  lumbar,  and  sacral  :  These  are  found  coming 
through  the  muscles  filling  the  spinal  gutter  in  two  sets,  an 
external  and  internal  set.  They  supply  the  overlying  mus- 
cles and  terminate  in  the  integument. 

Not  much  time  need  be  spent  in  dissecting  out  these 
nerves  ;   they  can  be  examined  as  the  dissection  proceeds. 

DISSECTION. 

Continue  to  remove  the  integument  from  the  forearm,  hand,  and  fingers,  as 
before  directed.     See  page  360. 

The  arrangement  of  the  superficial  veins  should  be  noted.  There  is  a  great 
amount  of  variation  in  their  formation.     The  usual  plan  is  given  below. 


Fig.  78.  Dissection  of  the  Forearm,  Posterior.  [Tiiis  specimen  presents  the 
"clubbed"  fingers  typical  of  tubercular  diathesis.] — 1,  Brachialis  anticus.  2,  Supinator  lon- 
gus  (brachioradialis).  3,  E.xtensor  carpi  radialis  longior.  4,  The  extensor  ossis  metacarpi 
poUicis.  5.  The  anterior  interosseous  artery,  having  passed  to  the  posterior  of  the  forearm. 
6,  Radial  nerve.  7,  Tendon  of  the  extensor  carpi  radialis  longior.  8,  Tendon  of  the  exten- 
sor carpi  radialis  brevior.  9,  Tendon  of  the  extensor  brevis  pollicis  (extensor  primi  inter- 
nodii  pollicis).  10,  Posterior  radial  carpal  arterv.  ii,  Dorsalis  pollicis  (which  also  gives  off 
the  dorsalis  indicis).  12,  Communicating  branch  between  the  radial  and  the  dorsal  cutaneous 
branch  of  the  ulnar  nerves.  13,  Radial  digital  branches.  14,  Extensor  longus  pollicis  (exten- 
sor secundi  internodii  pollicis).  15,  The  middle  portion  of  a  tendon  of  the  extensor  communis 
digitorum.  16,  The  lateral  portion  of  the  same  tendon.  17,  Slip  connecting  the  tendon  of 
the  extensor  communis  digitorum  of  the  ring  finger  with  that  of  the  middle.  18,  Tendon  of 
the  extensor  minimi  digiti.  ig,  Digital  branches  of  the  dorsal  cutaneous  nerve  (posterior 
carpal  of  ulnar).  20,  Tendons  of  the  extensor  communis  digitorum.  21,  The  posterior 
annular  ligament.  22,  The  extensor  indicis.  23,  Extensor  carpi  ulnaris.  24,  The  anconeus. 
25,  The  olecranon  process.     26,  The  external  condyle  of  humerus.     27,  Triceps. 


378  A  MANUAL   OF  ANA  TOMY. 

The  Superficial  Veins  of  the  Porearm. 

There  are  usually  two  main  trunks,  the  posterior  ulnar 
and  posterior  radial  veins.  These  begin  at  the  back  of  the 
hand  in  an  irregular  plexus  and  proceed  up  the  back  of  the 
forearm,  communicating  with  each  other  by  branches.  The 
posterior  ulnar  curves  forward  just  below  the  internal  con- 
dyle of  the  humerus  to  unite  with  the  anterior  ulnar  to  form 
the  common  ulnar.  See  page  282.  The  posterior  radial 
empties  into  the  radial  at  the  outer  side  of  the  upper  part 
of  the  forearm. 

The  Superficial  Nerves  of  the  Forearm  and  Hand — 

These  are — for  the  forearm  the  external  cutaneous  branch 
of  the  musculospiral  and  a  posterior  branch  of  the  cuta- 
neous portion  of  the  musculocutaneous  nerve,  for  the  outer 
half;  and  the  posterior  division  of  the  internal  cutaneous, 
for  the  inner  half  of  the  forearm. 

In  the  hand  the  radial  nerve  supplies  the  outer  half  of 
the  dorsum  and  the  outer  two  and  one-half  fingers,  while 
the  dorsal  cutaneous  branch  of  the  ulnar  nerve  completes 
the  inner  half  of  the  back  of  the  hand  and  two  and  one- 
half  fingers. 

DISSECTION. 

Remove  the  deep  fascia  from  the  back  of  the  forearm,  hand,  and  fingers. 
At  the  wrist  leave  a  band  of  the  deep  fascia  about  an  inch  wide,  the  posterior 
annular  ligament  of  the  wrist. 

Clean  all  the  muscles,  vessels,  and  nerves  presenting. 

The  Posterior  Annular  Ligament.      Fig.  78. 

This  will  be  found  to  consist  of  the  fibres  of  the  deep 
fascia  which  have  been  reinforced  by  additional  transverse 
fibres.  This  thickened  band  is  about  an  inch  wide,  and  is 
attached  from  the  outer  border  of  the  radius  around  the 
back   of  the  wrist  to  the  inner  border  of  the  pisiform  and 


UPPER  EXTREMITY  AND  THORAX,  POSTERIOR.      379 

cuneiform  bones.      It  is  not  attached  to  the  uhia,  but  passes 
over  it,  helping  to  hold  it  in  place. 

By  extensions  from  the  inner  surface  of  the  ligament  to 
the  ridges  of  the  radius,  the  grooves  upon  the  back  of  that 
bone  are  converted  into  canals,  through  which  the  long 
tendons  of  the  muscles  from  the  posterior  of  the  forearm 
to  the  hand  pass.      These  canals  are  arranged  as  follows  : — 


Diag.  24.  The  Annular  Ligament  of  the  Wrist  and  the  Approximate 
Relations  of  the  Various  Tendons.  (/.  S.  H.)—i,  Palmaris  longus.  2,  Middle 
compartment  of  annular  ligament,  anterior,  contains  the  tendons  the  flexor  sublimis 
and  profundus  digitorum,  the  flexor  longus  pollicis,  and  the  median  nerve.  3,  Flexor 
carpi  radialis.  4,  Extensor  ossis  metacarpi  pollicis,  extensor  brevis  pollicis.  5,  Ex- 
tensor carpi  radialis  longior  and  brevior.  6,  Extensor  longus  pollicis.  7,  Extensor 
indicis,  and  8,  Extensor  communis  digitorum  in  one  compartment.  9,  Extensor  minimi 
digiti.    10,  Extensor  carpi  ulnaris.    11,  Flexor  carpi  ulnaris.     12,  Ulna.     13,  Radius. 


Upon  the  outer  side  of  the  radius  are  the  tendons  of  the 
extensor  metacarpi  pollicis  and  the  extensor  brevis  pollicis  ; 
upon  the  back  of  the  radius  at  the  outer  side  are  the 
tendons  of  the  extensor  carpi  radialis  longior  and  brevior, 
separated,  however,  by  the  synovial  membrane  from  each 


380  A  MANUAL   OF  ANATOMY. 

other ;  next  is  the  extensor  longus  pollicis  in  a  narrow 
canal  ;  then  in  a  broad  one  lies  the  tendons  of  the  extensor 
communis  digitorum  and  the  extensor  indicis  ;  in  a  compart- 
ment behind  the  radio-ulnar  articulation  is  the  slender  ten- 
don of  the  extensor  minimi  digiti,  and  lastly,  lying  in  the 
groove  at  the  outer  side  of  the  styloid  process  of  the  ulna, 
is  the  tendon  of  the  extensor  carpi  ulnaris. 

Extensor  Carpi  Radialis  Longior.      Fig.  78. 

Origm. — From  the  lower  third  of  the  external  condyloid 
ridge  of  the  humerus  and  the  intermuscular  septa. 

Insertion. — Into  the  radial  side  of  the  base  of  the  second 
metacarpal  bone. 

Nerve  Stipply. — The  musculospiral  (fibres  from  the  sixth 
cervical  nerve). 

Action. — Extend  the  wrist,  feeble  flexor  of  forearm,  slight 
abductor  of  wrist. 

Extensor  Carpi  Radialis   Brevior.     Fig.  78. 

Origin. — By  the  common  tendon  from  the  external  (epi) 
condyle  of  the  humerus,  and  from  the  intermuscular  septa. 

Insertion. — Into  the  radial  side  of  the  base  of  the  third 
metacarpal  bone. 

Nerve  Supply. — The  posterior  interosseous  branch  of  the 
musculospiral.  The  fibres  coming  from  the  sixth  and  sev- 
enth cervical  nerves. 

Action. — To  extend  the  wrist,  slight  extensor  of  the  fore- 
arm. 

Extensor  Communis  Digitorum.     Fig.  78. 

Origin. — By  the  common  tendon  from  the  external  (epi) 
condyle  of  the  humerus,  and  from  the  intermuscular  septa, 
and  from  the  inner  surface  of  the  deep  fascia  of  the  forearm. 

Insertion. — The  muscle  is  provided  with  four  tendons 
which  pass  through   the  fourth  compartment  of  the  pos- 


UPPER  EXTREMITY  AND   THORAX,  POSTERIOR.      381 

tenor  annular  ligament  in  a  bunch.  Lower  down  they 
separate  to  pass  to  their  respective  fingers.  Across  the 
knuckles  the  tendons  of  the  three  outer  fingers  are  united 
by  fibrous  bands  which  diverge  fi'om  the  tendon  of  the  ring 
finger  to  the  tendons  of  the  middle  and  little  finger  on 
either  side.     The  insertion  into  the  fingers  is  as  follows  : — 

From  the  side  of  each  tendon  a  fibrous  extension  passes 
to  the  lateral  ligaments  of  the  metacarpophalangeal  articu- 
lations. Beyond  this  each  tendon  divides  into  three  slips. 
The  middle  slip  is  inserted  into  the  base  of  the  second 
phalanx,  the  two  lateral  slips  pass  forward  to  be  inserted 
into  the  base  of  the  last  phalanx. 

Each  tendon  of  the  extensor  communis  digitorum  re- 
ceives laterally  the  insertions  of  the  lumbricales  (see  page 
307)  and  the  dorsal  and  palmar  interossei  muscles  {^palmar, 
see  page  309  ;  dorsal,  page  388). 

Nerve  Supply. — The  posterior  interosseous  (the  filaments 
issue  from  the  seventh  cervical  nerve). 

Action. — To  extend  the  fingers,  hand,  and  wrist,  to 
slightly  extend  the  forearm. 

Extensor  Minimi  Digiti.      Fig.  78, 

Origin. — The  same  as  the  preceding,  with  which  it 
unites  for  the  upper  third  of  its  length. 

Insertion. — Into  the  tendon  of  the  common  extensor 
going  to  the  little  finger. 

Nerve  Supply. — Same  as  the  preceding. 

Action. — To  extend  the  little  finger,  the  hand,  and  the 
wrist,  and  a  very  feeble  extensor  of  the  elbow. 

Anconeus.      Fig.  78. 

Origin. — From  the  back  of  the  external  (epi)  condyle  of 
the  humerus,  and  from  the  posterior  ligament  of  the  elbow- 
joint. 


382  A  MANUAL   OF  ANA  TOMY. 

Insertion. — Into  the  outer  surface  of  the  olecranon,  and 
the  upper  fourth  of  the  uhia. 

Nerve  Supply. — The  musculospiral  (through  the  seventh 
and  eighth  cervical  nerves). 

Action. — To  extend  the  forearm. 

Extensor  Carpi  Ulnaris.  .  Fig.  78. 

Origin. — From  the  external  (epi)  condyle  of  the  humerus 
by  the  common  tendon,  from  the  upper  two-thirds  of  the 
posterior  ridge  of  the  ulna  in  common  Avith  the  flexor  carpi 
ulnaris  and  the  flexor  profundus  digitorum,  and  from  the 
inner  surface  of  the  deep  fascia  of  the  forearm  and  the  adja- 
cent intermuscular  septa. 

Insertion. — Into  the  back  of  the  base  of  the  metacarpal 
bone  of  the  little  finger. 

Nerve  Supply. — The  posterior  interosseous  (the  filaments 
from  the  eight  cervical). 

Action. — To  extend  the  wrist,  to  adduct  the  wrist,  to 
feebly  extend  the  forearm. 

DISSECTION. 

Separate  the  superficial  muscles  from  each  other  clear  to  their  origins ;  do 
not  remove  the  annular  ligament  yet  until  the  deeper  muscles  have  been  studied, 
after  which  it  can  be  cut  away  as  far  as  necessary  to  expose  the  relations  of 
the  tendons  to  each  other  and  to  the  back  of  the  wrist. 

Trace  the  recurrent  interosseous  artery  upward  to  the  elbow,  cutting  through 
the  auconeus  muscle.  Follow  downward  from  the  supinator  brevis,  the  pos- 
terior interosseous  artery  and  nerve,  the  former  to  its  anastomosis  with  the 
termination  of  the  anterior  interosseous,  and  the  latter  to  the  ganglion  upon  the 
back  of  the  wrist. 

Complete  the  cleaning  of  the  radial  artery  and  its  branches,  noting  the 
formation  of  the  posterior  carpal  anastomoses. 

Remove  the  fascia  from  the  interossei  muscles  and  demonstrate  their 
insertion. 

Extensor  Ossis  Metacarpi  Pollicis.      Fig.  79. 

Origin. — From    the   outer  surface  of  the  ulna  for  two 


Fig.  79.  Dissection  of  the  Forearm,  Posterior. — i,  External  condyle.  2,  Poste- 
rior interosseous  nerve  coming  through  the  supinator  brevis  muscle.  3,  The  posterior  inter- 
osseous arterv.  4,  Radius.  5,  Extensor  ossis  metacarpi  pollicis.  6,  Extensor  brevis  poUicis 
(extensor  primi  internodii  pollicis).  7,  Outer  branch  of  the  anterior  interosseous.  8, 
Tendon  of  the  extensor  carpi  radialis  brevior.  9,  Styloid  process  of  radius.  10,  Small  por- 
tion of  the  posterior  annular  ligament.  II,  Tendon  of  the  (divided)  extensor  longus  pollicis 
(extensor  secundi  internodii  pollicis).  12,  Posterior  carpal  arch,  radial  side.  13,  Radial 
nerve,  cutaneous  branch  to  thumb.  14,  Digital  arteries.  16,  Abductor  indicis,  first  dorsal  in- 
terosseous muscle.  17,  Anastomosis  of  dorsal  with  palmar  digital  arteries.  18,  The  three  inner 
interossei.  19,  Abductor  minimi  digiti.  20,  Tendon  of  the  extensor  carpi  ulnaris.  21,  Pos- 
terior carpal  arch,  ulnar  side.  22,  The  extensor  indicis.  23,  Ganglionic  enlargement  of  the 
posterior  interosseous  nerve  at  the  back  of  the  wrist-joint.  24,  Inner  division  of  the  anterior 
interosseous  artery.  25,  Posterior  interosseous  artery.  26,  The  same.  27,  The  ulna.  28. 
Recurrent  interosseous  artery.    29,  Anconeus.    30,  Olecranon  process. 


384  A  MANUAL   OF  ANATOMY. 

inches  above  the  middle,  from  the  middle  third  of  the 
posterior  surface  of  the  radius,  and  from  the  intervening 
portion  of  the  interosseous  membrane  between  its  bony- 
origins  ;  from  the  intermuscular  septa. 

Insei^tion. — Into  the  outer  aspect  of  the  base  of  the  first 
metacarpal  bone,  and  into  the  deep  fascia  of  the  ball  of  the 
thumb. 

Nerve  Siipply. — The  posterior  interosseous  (from  the 
seventh  cervical  nerve). 

Action. — Extensor  and  abductor  of  thumb,  abductor  of 
hand,  slight  supinator  of  forearm. 

Extensor  Brevis  Pollicis.  (Extensor  primi  internodii 
poUicis.)     Fig.  79. 

Origin. — From  the  posterior  surface  of  the  interosseous 
membrane  and  the  radius  below  the  above  muscle,  with 
which  it  is  continuous. 

Insertion. — Into  the  outer  surface  of  the  base  of  the 
first  phalanx  of  the  thumb. 

Nerve  Supply. — Same  as  the  above. 

Action. — To  extend  and  abduct  the  thumb,  to  abduct  the 
hand. 

Extensor  Longus  Pollicis.  (Extensor  secundi  internodii 
pollicis.)     Fig.  79. 

Origin. — From  the  posterior  surface  of  the  ulna  for  its 
middle  third,  from  the  adjoining  portion  of  the  interosseous 
membrane. 

Insertion. — Into  the  base  of  the  second  phalanx  of  the 
thumb. 

Nerve  Supply. — Same  as  the  above. 

Action. — To  extend  the  thumb  and  hand,  to  supinate  the 
forearm. 


UPPER  EXTREMITY  AND   THORAX,  POSTERIOR.      385 

Extensor  Indicis.      Pig.  79. 

Origin. — From  the  posterior  surface  of  the  uhia  and  the 
interosseous  membrane  just  below  the  extensor  longus  pol- 
licis. 

Insertion. — Into  the  tendon  of  the  common  extensor  for 
the  index  finger. 

Nerve  Siipply. — Same  as  tlie  above. 

Action. — To  extend  the  index  finger  and  hand. 

Supinator  Br e vis.      Figs,  dj ,  79. 

Origin. — By  the  common  tendon  from  the  external  (epi) 
condyle  of  the  humerus,  from  the  external  lateral  ligament 
of  the  elbow-joint,  from  the  orbicular  ligament,  from  the 
ridge  and  triangular  surface  of  bone  below  the  lesser  sig- 
moid cavity  of  the  ulna,  from  the  intermuscular  septa. 

Insertion. — Into  the  upper  third  of  the  radius  from  its 
neck  to  the  insertion  of  the  pronator  radii  teres  below,  and 
limited  by  the  oblique  line  in  front. 

Nei've  Supply. — The  posterior  interosseous,  which  passes 
through  the  muscle  from  the  front  to  the  back  of  the  fore- 
arm.     (The  fibres  come  from  the  sixth  cervical  nerve.) 

Action. — To  supinate  the  forearm. 

The  Posterior   Interosseous    Artery.      (See    page    297.) 
Fig.  79. 
This  is  a  branch  from  the   common  interosseous  in  the 
anterior  part  of  the  forearm.      It  turns  backward,  passing 
between  the  radius  and  ulna  on  either  side,  and  the  interos- 
seous membrane  below,  and  the  oblique  ligament  above,  and 
appears  in  the  posterior  part  of  the  forearm  between  the 
supinator  brevis  and  the  extensor  ossis  metacarpi  pollicis 
muscles.      It   descends   between    the   deep   and   superficial 
layers  of  muscles  until  just  above  the  wrist  it  terminates  in 
branches  which   anastomose  with  the  anterior  interosseous 
25 


386  A  MANUAL   OF  ANATOMY. 

and  the  posterior  carpal  branch  of  the  radial.  Its  branches 
are  distributed  to  the  surrounding  muscles  and  to  the  wrist- 
joint. 

The  Posterior  Interosseous  Nerve.     Fig.  79. 

Is  a  branch  from  the  musculospiral  just  above  the  exter- 
nal (epi)condyle  in  the  interval  between  the  supinator  longus 
and  the  brachialis  anticus.  See  page  318.  It  descends  to 
the  anterior  surface  of  the  supinator  brevis,  through  which 
it  passes  to  the  back  of  the  forearm,  where  it  is  found  under 
the  superficial  layer  of  muscles.  As  it  descends  it  passes 
under  the  deep  muscles  to  the  interosseous  membrane,  upon 
which  it  lies,  and  ends  just  above  the  wrist-joint  in  a  small 
ganglion. 

The  nerve  gives  off  branches  to  all  the  muscles  at  the  back 
of  the  forearm  and  the  ganglion,  to  the  wrist  and  carpal 
joints. 

The  Termination  of  the  Anterior  Interosseous  Artery. 
Fig.  79. 
This  is  found  coming  through  the  interosseous  membrane 
about  an  inch  and  a  half  above  the  wrist.  It  descends  to 
the  back  of  the  wrist,  where  it  enters  into  an  anastomosis 
with  the  posterior  carpal  of  the  radial.  In  its  course  it 
forms  an  anastomosis  with  the  posterior  interosseous  above 
the  wrist. 

The  Recurrent  Interosseous  Artery.      Fig.  79. 

Is  a  branch  of  the  common  or  the  posterior  interosseous. 
It  is  found  on  the  back  of  the  forearm  as  it  curves  upward 
over  the  supinator  brevis.  It  runs  upward  between  this 
muscle  and  the  anconeus  to  the  back  of  the  elbow-joint 
between  the  external  (epi)  condyle  and  the  olecranon  pro- 
cess, where  it  enters  into  the  elbow  anastomosis. 


UPPER  EXTREMITY  AND  THORAX,  POSTERIOR.      387 

The  arteries  -which  form  the  anastomosis  about  the 
elbo-w-joint  are  the  follo-wing- : — In  front  of  the  elbow  : 
On  the  outer  side  there  is  the  termination  of  the  superior 
profunda  above  and  the  recurrent  radial  below  ;  on  the 
inner  side  the  anterior  branch  of  the  anastomotica  magna 
above  and  the  anterior  ulnar  recurrent  below. 

Behind  the  elbow  :  On  the  outer  side  the  articular  branch 
of  the  superior  profunda  above,  and  the  recurrent  interos- 
seous below  ;  on  the  inner  side  the  posterior  branch  of  the 
anastomotica  magna  and  the  inferior  profunda  above,  with 
the  posterior  ulnar  recurrent  below. 

On  the  back  of  the  elbow  all  these  arteries  inosculate  to 
form  a  free  plexus  and  communication  with  each  other. 

The  Radial  Artery  at  the  "Wrist.      Fig.  79. 

Continuing  the  description  of  the  artery  from  the  lower 
end  of  the  radius  where  it  was  left  off,  see  page  293. 

The  artery  is  seen  to  run  backward  around  the  lower  end 
of  the  radius,  between  the  tendons  of  the  extensor  ossis 
metacarpi  and  brevis  pollicis  and  the  external  lateral  liga- 
ment of  the  wrist-joint,  to  the  interval  between  the  bases  of 
the  first  and  second  metacarpal  bones,  where  it  lies  under  the 
tendon  of  the  extensor  longus  pollicis  muscle.  It  now 
passes  forward  and  inward  between  the  first  and  second 
metacarpal  bones  and  the  two  heads  of  the  abductor  indicis 
muscle  to  the  palmar  side  of  the  hand,  where  it  is  continued 
as  the  deep  arch.      See  page  310. 

The  Branches  of  the  Radial  at  the  Back  of  the  Wrist. — 
(i)  The  posterior  carpal  arises  as  the  radial  issues  from 
under  the  tendon  of  the  extensor  brevis  pollicis,  runs 
inward  across  the  back  of  the  wrist,  and  terminates  by  anas- 
tomosing with  the  posterior  ulnar  carpal  and  the  anterior 
and   posterior   interosseous  arteries.      From  this   posterior 


388  A  MANUAL   OF  ANATOMY. 

carpal  arch  the  second  and  third  dorsal  interosseous  arteries 
are  distributed  to  the  third  and  fourth  interosseous  spaces. 
(2)  The  first  dorsal  interosseous,  or  the  metacarpal :  a  small 
branch  fi-om  the  radial  under  the  tendon  of  the  extensor 
longus  pollicis,  to  the  space  between  the  second  and  third 
metacarpal  bones.  (3)  The  dorsalis  pollicis  and  (4)  the 
dorsalis  indicis  are  small  arteries  distributed  to  the  dorsal 
surface  of  the  thumb  and  index  fingers.  The  dorsalis  pol- 
licis divides  into  two  branches  to  either  side  of  the  thumb, 
while  the  dorsalis  indicis  supplies  the  outer  side  of  the  index 
finger. 

The  Collateral  Digital  Arteries. 

The  dorsal  digital  arteries  divide  at  the  web  of  the  fingers 
into  small  branches  to  the  adjacent  sides  of  the  dorsal 
surface  of  the  fingers. 

The  posterior  carpal  branch  of  the  ulnar  is  found  issu- 
ing from  the  front  of  the  forearm  under  the  tendon  of  the 
flexor  carpi  ulnaris  muscle.  It  passes  to  the  back  of  the 
wrist  and  enters  into  the  posterior  carpal  anastomoses.  See 
above. 

The  Dorsal  Interossei.      Fig.  79. 

These  are  four  in  number,  one  on  either  side  of  the 
middle  finger,  one  to  the  radial  side  of  the  index,  and  one 
to  the  ulnar  side  of  the  ring  finger  respectively. 

Origin. — By  two  heads  from  the  contiguous  sides  of  the 
metacarpal  bones  between  which  they  lie.  The  origin  is 
more  extensive  from  that  metacarpal  bone  of  the  finger 
into  which  they  are  inserted. 

Insertion. — Into  the  base  of  the  first  phalanx,  and  into 
the  lateral  margin  of  the  tendon  of  the  extensor  communis 
dieitorum. 


UPPER  EXTREMITY  AND   THORAX,  POSTERIOR.      389 

Nerve  Supply. — The  ulnar  through  the  deep  palmar 
branch  (the  filaments  coming  from  the  eighth  cervical 
nerve). 

Action. — To  extend  the  second  and  third  phalanges,  to 
flex  the  first  phalanges  of  the   four  fingers   to  which   they 


Diag.  25.  Diagram  of  the  Insertion  of  the  Lumbricales  and  Interossei 
Muscles  into  the  Aponeurotic  Tendon  of  the  Extensor  Communis  Digi- 
TORUM,  to  Illustrate  their  Double  Action  as  Flexors  of  the  First  Phalanges 
and  Extensors  of  the  Last  Two  Sets  of  Phalanges.    (/.  .S".  //,) 


are  attached.  This  action  is  in  common  with  the  palmar 
set  of  interossei,  and  the  lumbricales.  The  distinctive  action 
of  the  dorsal  set  of  muscles  is  abduction  of  the  fingers 
from  a  line  throug-h  the  middle  finger. 


THE  SPINAL  CORD. 

DISSECTION. 

The  dissection  of  the  spinal  cord  is  not  practicable  in  the  usual  dissecting- 
room  subject,  for  the  cord  is  so  soft  that  its  gross  structure  cannot  be  deter- 
mined. 

A  perfectly  fresh  subject  that  has  been  injected  as  soon  as  received,  or  a 
"pickled  subject"  that  has  been  preserved  with  a  zinc  injection  and  a  hard- 
ening preservative  solution,  is  to  be  selected. 

If  the  brain  has  been  removed  as  previously  described,  the  dissection  can 
be  continued  by  cleaning  out  all  the  mass  of  muscles  which  fill  in  the  spinal 
gutters  from  the  base  of  the  skull  to  the  end  of  the  sacrum.  Clean  the  spi- 
nous processes,  laminae,  and  articular  processes,  noting  the  ligaments  of  these 
parts  of  the  spine. 


390  A  MANUAL  OF  ANATOMY. 

Beginning  above  with  a  pair  of  curved  bone  cutters  (having  a  blunt-pointed 
lower  blade),  carefully  sever  all  the  laminae  on  both  sides  from  above  down- 
ward, keeping  as  close  to  their  outer  extremities  as  possible.  Remove  the 
laminae,  the  spinous  processes,  and  connecting  ligaments.  Clean  the  posterior 
surface  of  the  dura.  Carefully  trace  outward  the  nerve  trunks  as  they  pass 
from  the  dura  to  enter  the  intervertebral  foramina. 

Open  the  dura  carefully  from  above  downward. 

The  Spinal  Dura.      Figs.  80,  81. 

This  membrane  is  similar  in  structure  to  the  cranial  dura, 
with  which  it  is  continuous  at  the  foramen  magnum.  It 
differs  in  this  point  that  it  does  not  in  the  spine  form  the 
inner  periosteum  for  the  vertebrae  as  it  does  for  the  cranial 
bones,  though  it  is  connected  to  the  periosteum  and  liga- 
ments of  the  former  by  a  loose  connective  tissue.  It  extends 
from  the  foramen  magnum  to  about  the  second  or  third 
sacral  vertebra,  beyond  which  it  is  prolonged  as  a  cord-like 
sheath  for  the  fllum.  terminale  of  the  cord,  and  is  attached 
to  the  base  of  the  coccyx. 

The  dura  is  pierced  by  the  spinal  nerve,  around  which 
it  is  prolonged  in  the  shape  of  funnel-like  sheaths  for  a 
short  distance,  until  it  blends  with  the  sheaths  of  the 
nerves. 

The  inner  surface  of  the  dura  is  smooth,  as  in  the  brain, 
and  is  separated  in  a  similar  manner  from  the  arachnoid 
membrane  by  the  subdural  space.  The  spinal  dura  does 
not  send  processes  into  the  fissures  of  the  cord. 

The  Spinal  Arachnoid. 

This  reaches  as  low  as  the  dura,  to  the  inner  surface  of 
which  it  is  closely  applied  (but  separated  from  it  by  the 
subdural  space,  which  in  the  normal  condition  is  very  nar- 
row). It  surrounds  the  nerves  within  the  tubular  sheaths 
of  the  dura  and  terminates  like  that  membrane  by  becom- 
ing continuous  with  the  sheaths  of  the  nerves. 


Fig.  80.  Dissection  of  the  Spinal  Cord.  [Photograph  of  the  first  prize  dissec- 
tion at  the  University  Medical  College,  1895,  by  J.  J.  Moorhead.]— The  dura  not  opened. 
The  tubular  processes  which  pass  outward  enclosing  each  pair  of  the  spinal  nerves  are 
well  shown. 


392  A  MANUAL   OF  ANATOMY. 

The   Spinal  Pia.      Fig.  8i. 

This,  like  in  the  brain,  is  the  vascular  membrane  which 
encloses  the  cord  from  the  foramen  magnum  to  the  end  of 
the  cord  proper  at  the  second  lumbar  vertebra,  beyond 
which,  under  the  name  of  the  filum  terminale  (mostly  pia 
but  little  cord),  it  extends  to  the  base  of  the  sacrum. 

From  the  lateral  margins  of  the  cord  (pia)  saw-teeth-like 
processes  pass  outward  to  be  attached  by  the  apices  of  the 
teeth  to  the  inner  surface  of  the  dura  (and  thus  pin  the  arach- 
noid to  the  dura  at  these  points).  There  are  21  of  these 
teeth,  and  they  are  termed  the  ligamentum  denticulatum. 
They  serve  to  hold  the  cord  steadily  in  its  proper  position 
within  the  centre  of  the  spinal  canal. 

The  space  between  the  arachnoid  and  the  pia  is  the  spinal 
subarachnoidean  space  and  communicates  with  the  similar 
spaces  of  the  brain.  It  contains  the  cerebrospinal  fluid, 
which  can  thus  flow  freely  from  the  spinal  canal  into  the 
subarachnoid  spaces  at  the  base  of  the  brain,  and  thence  by 
way  of  the  foramen  of  Majendie  into  the  ventricular  cavi- 
ties of  the  same. 

The  pia  dips  into  the  anterior  and  posterior  fissures  of  the 
cord. 

The  pia  and  arachnoid  are  connected  by  filaments  of 
connective  tissue  constituting  the  subarachnoid  tissue.  It 
becomes  thickened  around  the  vessels  which  pass  to  (and 
from)  the  cord  at  its  posterior  fissure  and  here  forms  an  in- 
complete partition  called  the  septum. 

The  Spinal  Cord.      Fig.  81. 

The  spinal  cord  is  16  to  18  inches  in  length,  ex- 
tending from  the  margin  of  the  foramen  magnum  to  the 
first  or  second  lumbar  vertebra.  Its  diameter  is  from  two- 
to  three-fifths    of  an  inch.     It  weighs  about  one    ounce. 


Fig.  8i.  Dissection  of  the  Spinal  Cord.  [Photograph  of  the  first  prize  dis- 
section at  the  University  Medical  College,  1S95,  by  J.  J.  Moorhead.]— a,  Dura  of  cord 
reflected,  b,  Arachnoid  and  pia  of  cord  still  enveloping  it.  The  former  membrane 
is  very  thin  and  cannot  be  demonstrated  in  such  a  dissection.  The  pia  and  its  vascu- 
lar construction  is  apparent,  c,  One  of  the  spinal  nerve  roots.  Many  of  the  others 
are  shown,     d,  The  cauda  equina,     e.  The  great  sciatic  nerve. 


394  ^4  MANUAL  OF  ANATOMY. 

Its  sections  are  generally  cylindrical,  except  in  the  cervical 
region,  where  they  become  slightly  flattened  from  before 
backward.  It  is  divided  into  three  regions,  cervical  (four 
inches  long),  the  dorsal  (ten  and  one-half),  and  the  lumbar 
(the  rest  of  the  cord).  In  the  first  and  third  regions,  the 
cord  is  slightly  enlarged  and  forms  the  cervical  and  lumbar 
enlargements. 

The  cervical  enlargement  extends  from  the  third  cervi- 
cal to  the  second  dorsal  vertebra.  The  lumbar  from  the 
ninth  to  the  last  dorsal  or  first  lumbar  vertebra. 

The  cord  is  divided  by  two  incomplete  fissures  into  two 
symmetrical  halves.  The  central  substance  which  con- 
nects the  halves  of  the  cord  is  the  commissure,  and  within 
it  is  a  minute  canal,  the  central  canal  of  the  cord,  which 
opens  into  the  fourth  ventricle  at  the  calamus  scriptorius. 
It  is  the  remains  of  the  central  canal  which  extended  through 
the  primitive  cerebrospinal  axis. 

The  anterior  fissure  of  the  cord  is  a  wider  but  shal- 
lower fissure  than  the  posterior,  which  is  narrow  and  deep. 
The  first  is  one-third,  the  second  one-half  of  the  anteropos- 
terior diameter  of  the  cord.  These  fissures  are  co-ex- 
tensive with  the  anterior  and  posterior  fissures  of  the 
medulla. 

The  surface  of  the  cord  is  further  divided  by  two  shallow 
grooves — the  anterolateral  and  posterolateral, — from  which 
issue  the  anterior  and  posterior  nerve  roots,  into  three 
tracts,  the  anterior,  lateral,  and  posterior.  Here  it  is  ap- 
parent that  the  anterior  tract  is  continuous  with  the  pyra- 
midal tract  of  the  medulla,  the  lateral  with  the  lateral,  and 
the  posterior  into  the  funiculi  gracilis  and  cuneatus  of  the 
medulla. 

On  section,  the  characteristic  arrangement  of  the  white 
and  gray  matter  of  the  cord  becomes  apparent.     The  gray 


THE  SPINAL  CORD.  395 

matter  is  enclosed  within  the  white,  and  exists  in  the  shape 
of  two  large  "  commas  "  ('),  turned  with  the  head  anterior, 
the  convex  surfaces  turned  toward  each  other,  and  con- 
nected at  their  middle  by  the  gray  commissure. 

Here  we  must  pause.  The  subject  of  the  internal  arrange- 
ment of  the  cord  and  brain  is  most  fascinating,  but  it  does 
not  properly  enter  into  the  scope  of  such  a  manual  of 
anatomy  as  this.  However,  the  student  should  not  be  con- 
tent to  let  the  matter  rest  here,  but  should  pass  from  this 
hasty  and  necessarily  incomplete  description  of  the  brain 
and  cord  to  the  microscopic  anatomy  of  the  same,  then  to 
their  functions,  and  lastly  to  the  application  of  all  this 
knowledge  to  the  workings  of  medical  and  surgical  practice. 

The  Spinal  Nerves.     Fig.  8 1 . 

They  arise  from  the  side  of  the  cord  in  32  pairs  by  two 
sets  of  roots  as  already  indicated,  the  anterior  (motor) 
and  posterior  (sensory),  the  former  being  smaller  than 
the  latter.  Inasmuch  as  the  spinal  cord  does  not  reach 
to  the  lower  extremity  of  the  spinal  canal,  it  follows  that,  as 
the  spinal  nerves  leave  the  cord  they  have  to  descend  in 
order  to  leave  by  their  proper  foramen,  the  downward 
inclination  of  the  nerves  increases  from  above  downward, 
until  at  the  lower  end  of  the  cord  the  canal  is  filled  with  the 
nerves  from  below  the  last  dorsal  vertebra,  which  run 
parallel  with  each  other  and  then  slightly  outward  to  reach 
their  foramen  of  exit ;  this  arrangement  produces  a  tasseled 
appearance  named  the  cauda  equina. 

The  point  at  which  the  spinal  nerves  leave  the  side  of 
the  cord  and  their  points  of  emergence  are  given  in  the 
following  table  copied  from  Gowers  : — 


396 


A  MANUAL  OF  ANATOMY. 


St.  xMastoid. 
Trapezius. 

Diaphragm. 

\  Serratus. 
)  Slioulder.  "1 


Arm. 

Hand. 
(Ulnar  lowest.) 


mus. 


Intercostal 
muscles. 


Abdominal 
muscles. 


Flexors,  hip. 

Extensors,  knee. 
\  Adductors.    -, 

[Abductors.        |-  hip. 
I  I 

J  Extensors  (?)    J 
I  Flexors,  knee  (?) 
VMuscles  of  leg 
)      moving  foot. 
Perineal  and  Anal 
muscles 


Knee-jerk. 


I 

Gluteal 


f  outer  side. 

Thigh  -I    front. 

I.  inner  side. 
Leg,  inner  side. 

f  Buttock,  lower 

I      part. 

I  Back  of  Thigh. 

I  Leg    "I   except  Foot-clonus. 

I  and      >  inner 

[  Foot    )   part  Plantar 

1  Perineum  and 
j      Anus. 

\  Skin  from  Coccyx 
J      to  Anus. 


Diagram  and  Table  showing  the  Approximate  Relation  to  the  Spinal  Nerves  of 
the  Various  Motor,  Sensory,  and  Reflex  Functions  of  the  Spinal  Cord  {from  anatom- 
ical and  pathological  data). 


\  Neck  and  Scalp. 


Neck  and  Shoulder. 

Shoulder. 

Arm. 

Hand. 


Front  of  Thorax. 
\  Ensiform  area. 


Abdomen 
("(Umbilicus,  loth). 

I  1  Buttock,  upper 

J  i      part. 
)  Groin  and  Scrotum 
;      (front) 


►  Scapular. 


Epigastric. 


■Abdominal. 


■  Cremasteric. 


THE  PERINEUM,  MALE.  397 

THE  PERINEUM,  Male. 

The  perineum  is  a  diamond-shaped  space  corresponding 
to  the  boundaries  of  the  pelvic  outlet. 

The  pelvic  outlet  is  formed  by  the  lower  borders  of  the 
ossa  innominata  joined  in  front  at  the  symphysis  and  be- 
hind by  the  wedge-shaped  sacrum. 

Landmarks. 

The  borders  of  the  perineal  space  can  be  felt,  and  are 
formed  by  the  under  surface  of  the  pubic  arch,  in  front ; 
the  rami  of  the  pubes  and  ischium,  and  the  tuberosities  of 
the  latter,  at  the  side  anteriorly  ;  the  lower  border  of  the 
gluteus  maximus,  beneath  which  can  be  outlined  the  great 
sacrosciatic  ligaments,  at  the  side  posteriorly  ;  and  the  tip 
of  the  coccyx  in  the  posterior  median  line. 

In  the  median  line,  in  front  of  the  coccyx,  is  the  anus, 
and  in  front  of  the  anus  reaching  up  to  the  base  of  the 
scrotum  is  the  bulb  of  the  penis. 

Laterally,  in  the  anterior  part  of  the  perineum,  the  crura 
of  the  penis  will  be  felt  covering  the  ischiopubic  rami  ; 
and  posteriorly,  at  the  side  of  the  anus,  is  a  depression 
filled  with  fat — the  ischiorectal  fossa. 

The  perineum  is  divided  by  a  transverse  line  from  the 
tuberosities  of  the  ischium  into  the  anterior  compartment, 
or  the  perineum  proper,  and  the  posterior  division,  or  the 
ischiorectal  fossae. 

In  order  to  understand  the  construction  of  the  pelvic 
floor  it  will  be  well  to  first  study  the  arrangement  of  the 
fasciae  which  assist  in  closing  the  pelvic  outlet  and  support 
the  pelvic  viscera  in  position.  Start  from  the  interior  of 
the  pelvis.  Attached  to  the  inner  surface  of  the  obturator 
membrane  and   the   margin  of  the  bone   adjacent  thereto, 


398 


A  MANUAL   OF  ANATOMY. 


especially  posteriorly  and  below,  is  the  obturator  internus 
(see  Fig.  114);  and  covering  over  the  front  of  the  sacrum 
is  the  pyriformis,  which  disappears  through  the  greater 
sacrosciatic  foramen.  These  muscles  are  covered  by  the 
obturator  and  pyriformis  fascia  respectively. 

The  Obturator  Fascia.     Fig.  113.      Diags.  26,  27. 

It  covers  the  obturator  internus   and  is  attached   to  the 
inner  surface  of  the  pelvis  around  the  origin  of  the  muscle  ; 


Diag.  26.  The  Attachments  of  the  Pelvic  Fascia.  [Modified  from  Morris, 
I.  S.  H.) — I,  Levator  ani  muscle.  2,  Perineal  fascia.  3,  Anterior  laj-er  of  triangular 
ligament.  4,  Posterior  layer  of  triangular  ligament.  5,  Compressor  urethras  muscle. 
(Deep  transversus  perineae.)  6,  Erector  penis  (Ischiocavernosus).  7,  The  "white 
line."  8,  Origin  of  the  obturator  internus.  9,  Iliopectineal  line.  10,  Dotted  line 
shows  attachment  of  the  obturator  fascia. 


above,  to  the  iliopectineal  line  ;  in  front,  to  the  inner  surface 
of  the  pubes  a  little  external  to  the  symphysis,  to  the  inner 
lip  of  the  rami  of  the  pubes  and  ischium  ;  below,  to  the  inner 


THE  PERINEUM,  MALE.  399 

lip  of  the  tuberosity  of  the  ischium,  blending  with  the  falci- 
form extension  of  the  great  sacrosciatic  ligament ;  behind, 
about  the  margin  of  the  great  sacrosciatic  notch  and  to  the 
front  of  the  articular  surface  for  the  sacrum,  and  continuous 
above  with  the  posterior  end  of  the  iliopectineal  line.  By- 
its  attachment  to  the  great  sacrosciatic  ligament  the  fascia 
is  carried  over  the  lesser  sacrosciatic  foramen  ;  underneath 
the  ligament  an  extension  of  the  fascia  is  prolonged  out- 
ward, with  the  obturator  internus  muscle,  into  the  gluteal 
region. 

The  obturator  fascia  is  continuous  behind  with  the  thin 
membrane  covering  the  pyriformis  muscle  ;  at  its  anterior 
part  it  is  pierced  by  the  obturator  nerve  and  vessels.  It  is 
crossed  obliquely  from  above  downward  by  the  line  of  at- 
tachment of  the  rectovesical  fascia,  the  so-called  "  white 
line,"  which  curves  downward  and  backward  from  the  inner 
and  upper  surface  of  the  pubes  across  the  middle  of  the 
obturator  foramen  and  ends  at  the  base  of  the  spine  of  the 
ischium.  The  obturator  fascia  above  the  "white  line"  is 
within  the  pelvic  portion  of  the  abdominal  cavity,  and  is 
covered  by  peritoneum  ;  the  portion  below  is  extrapelvic 
and  belongs  to  the  perineum.  This  perineal  or  anal  portion 
furnishes  a  canal  (of  Alcock)  through  which  the  pudic 
vessels  pass. 

The  Psrriforniis  Fascia.      Fig.   113. 

This  is  a  thin  membrane  covering  the  muscle  and  sciatic 
plexus  of  nerves.  It  is  adherent  about  the  origin  of  the 
pyriformis  and  blends  in  front  with  the  obturator  and  recto- 
vesical fasciae. 

The  Rectovesical  Fascia.      Fig.  113.      Diags.  26,  27,  28. 

This    may    be    said   to    come  off  the    inner    surface   of 

the  obturator  fascia  along  a   line  reaching  from  the  inner, 


400 


A  MANUAL  OF  ANA  TOMY. 


Upper  surface  of  the  body  of  the  pubes  to  the  spine  of  the 
ischium.  This  fascial  line  is  slightly  concave  upward,  and 
from  its  appearance  is  called  the  "  white  line." 

Posteriorly  the   rectovesical  fascia  blends  with  the  pyri- 
formis  fascia.      In  the  ansTular  interval  between  the  recto- 


Diag.  27.  Transverse  Section  of  Pelvis  through  Anterior  Portion  of 
Perineum.  {Modified from  Quain,  I.  S.  //.)— i,  Bladder.  2,  Dotted  line  to  show  the 
extent  to  which  the  vesical  reflection  of  the  rectovesical  fascia  reaches.  3,  Base  of 
bladder  and  seminal  vesicles.  4,  Prostate  enclosed  in  its  capsule  of  rectovesical  fascia. 
5,  Urethra.  6,  Bulb  of  corpus  spongiosum.  7,  Rectovesical  fascia.  8,  Levator  ani 
muscle.  9,  Deep  layer  of  triangular  ligament.  10,  Compressor  urethra  muscle. 
II,  Superficial  layer  of  triangular  ligament.  12,  Accelerator  urinse.  13,  Erector  and 
crus  penis.     14,  Perineal  fascia.     15,  Obturator  internus  muscle.    16,  Obturator  fascia. 


vesical  and  obturator  fasciae  the  levator  ani  muscle  is 
attached  (along  the  so-called  "  white  line  ").  The  recto- 
vesical fascia  drops  downward  and  inward,  covering  the 
upper  surface    of  the  levator  ani  (and   coccygeus  muscles). 


THE  PERINEUM,  MALE.  401 

reaching  to  the  bladder,  prostate,  and  rectum.  Beneath 
these  structures  the  fascia  is  continuous  with  the  similar 
layer  from  the  opposite  side.  The  fiiscia  thus  com- 
pletely closes  the  pelvic  outlet  and  supports  the  pelvic 
viscera. 

At  the  side  of  the  rectum,  bladder,  and  prostate  the 
fascia  splits  into  two  layers, — an  upper  layer  that  is  reflected 
upward  on  to  the  rectum  for  a  distance  of  two  inches  or  so 
and  becomes  lost  ;  on  to  tiie  bladder  it  reaches  upward  above 
the  seminal  vesicles  (thus  shutting  them  out  from  the  pelvic 
cavity  proper),  then  merges  into  the  wall  of  the  bladder. 
The  low'er  layer  is  continued  inward  to  join  the  opposite 
layer  beneath  the  bladder,  and  also  sends  a  lamina  down- 
ward to  enclose  the  prostate,  form  its  capsule,  and  become 
continuous  with  the  deep  layer  of  the  triangular  ligament. 
Between  the  fascia,  bladder,  and  prostate  lies  a  collection 
of  large  veins  known  as  the  vesicoprostatic  plexus.  The 
rectum  lies  in  close  contact  with  the  prostate  and  the  base 
of  the  bladder,  separated  from  them  only  by  a  layer  of  the 
rectovesical  fascia,  which  is  reflected  upward  and  downward 
upon  it.  The  lower  layer  is  lost  in  the  muscular  tissue  of 
the  rectum  above  the  anus  ;  the  upper  reflection  can  be 
traced  about  two  inches,  when  it,  too,  is  lost  in  the  sub- 
stance of  the  bowel. 

The  portions  of  the  fascia  reaching  to  the  rectum  are 
called  the  true  lig-araents  of  the  rectum,  and  the  portions 
reaching  to  the  sides  of  the  bladder  are  Hkewise  called  the 
lateral  true  ligaments  of  the  bladder.  Besides  these  liga- 
ments (all  parts  of  the  same  fascial  plane)  the  fascia  which 
extends  from  both  sides  of  the  inner  surface  of  the  pubes  to 
the  front  of  the  neck  of  the  bladder  and  prostate  are  called 
the  anterior  true  lig-aments  of  the  bladder  and  prostate. 
These  are  the  best  marked,  and  contain  involuntaiy  muscu- 
26 


402  A  MANUAL   OF  ANATOMY. 

lar  fibres.      They  are  also  called  the  puboprostatic  liga- 
ments. 

In  the  female  the  rectovesical  fascia  encloses  the  vagina 
and  forms  a  sheath  for  it  similar  to  the  prostate  in  the  male. 

The  Anal  (Ischiorectal)  Fascia.      Diags.  27,  28.     Fig.  %2. 

This  is  a  thin  layer  which  covers  the  lower  surface  of  the 
levator  ani  muscle  and  coccygeus  muscles.  Laterally,  it 
is  attached  to  the  obturator  fascia  close  under  the  origin  of 
the  levator  ani  muscle  from  the  "  white  line  ;  "  behind,  it 
blends  with  the  obturator  fascia  ;  in  front,  it  becomes  con- 
tinuous with  the  triangular  ligament ;  centrally,  it  passes 
into  the  fibrous  tissue  about  the  anus. 

The  prismatic-shaped  cavity  which  is  left  between  the 
lower  part  of  the  obturator  fascia  and  the  anal  fascia  is  called 
the  ischiorectal  fossa. 

The  Deep  Layer  of  the  Triangular  Lig-ament.  Diags. 
26,  27,  28. 

Posteriorly,  this  ligament  becomes  continuous  with  the 
anal  fascia  (also  the  superficial  layer  of  the  triangular  liga- 
ment and  the  perineal  fascia,  as  will  appear  later).  Later- 
ally, it  is  attached  all  along  the  inner  margin  of  the  rami  of 
the  ischium  and  pubes  ;  anteriorly,  to  the  subpubic  ligament, 
leaving  here  an  opening  for  the  single  dorsal  vein  of  the 
penis.  The  upper  surface  of  the  deep  layer  of  the  triangular 
ligament  is  continuous  at  the  anterior  margin  of  the  levator 
ani  muscle  with  the  rectovesical  fascia,  which  here  forms  the 
capsule  for  the  prostate  gland.  The  prostate  gland  rests 
upon  this  portion  of  the  triangular  ligament  as  on  a  shelf 

The  triangular  ligament  (deep  portion)  is  perforated  at 
its  apex  by  the  dorsal  vein  of  the  penis  ;  at  its  base  centrally, 
by  the  membranous  urethra  ;  at  its  base  laterally,  by  the 
pudic  artery,  vein,  and  dorsal  nerve  of  the  penis. 


THE  PERINEUM,  MALE. 


403 


In  the  female  this  fascia  is  split  for  the  passage  of  the 
vagina. 


72  3  ^ 


Diag.  28.  Median,  Vertical  Anteroposterior  Section  of  Male  Pelvis. 
{Based  un  Sappey,  I.  S.  H.) — i,  Skin.  2,  Superficial  fascia.  (Scarpa's  on  abdomen, 
dartos  011  penis  and  scrotum,  Colles'  or  perineal  in  the  perineum.)  3,  Muscle  wall  of 
abdomen.  4,  Peritoneum,  reflected  over  bladder  and  rectum.  5,  Bladder.  6,  Rectum. 
7,  Retzius'  space.  8,  Rectovesical  pouch.  9,  9,  Rectovesical  fascia.  The  anterior 
thickened  portion  forms  the  puboprostate  ligament.  10,  Deep  layer  of  triangular 
ligament.  11,  Compressor  urethrae  (deep  transversus  perineae).  12,  Superficial  layer 
of  the  triangular  ligament.  13,  Cowper's  gland  and  duct.  14,  Internal  meatus  of 
urethra.  15,  Seminal  vesicle,  shut  out  from  general  abdominal  cavity  by  upward 
reflection  of  rectovesical  fascia.  16,  Prostate  gland  enclosed  within  a  capsule  formed 
by  the  downward  extension  of  the  rectovesical  fascia.  17,  Levator  ani  muscle.  18,  Anal 
fascia.  19,  Meeting  point  (really  line)  of  two  layers  of  triangular  ligament,  the  perineal 
and  anal  fasciae.  20,  Bulb  of  corpus  spongiosum.  21,  Sphincter  ani.  Figs.  iS  and  19 
are  placed  within  the  ischiorectal  fossa.  22,  Prostate.  23,  Membranous  and  24, 
Spongy  parts  of  urethra. 

The    Superficial    Layer  of  the    Triangular    Ligament. 
Diags.  26,  27,  28. 
This  is  attached  alongf  the  inner  maro-in  of  the  ramus  of 


404  A  MANUAL   OF  ANATOMY. 

the  ischium  and  pubes  external  to  the  Hne  of  the  deep 
fascia.  Behind,  it  is  continuous  with  the  deep  layer  ;  in 
front,  it  extends  to  the  subpubic  ligament  and  is  pierced 
here  for  the  dorsal  vein,  arteries,  and  nerves  of  the  penis. 

It  is  separated  from  the  deep  layer  by  the  compressor 
urethras  muscle,  imbedded  in  which  are  the  dorsal  nerve 
and  vein  of  the  penis,  the  internal  pudic  artery  and  its 
branches  to  the  bulb,  the  crus,  and  the  dorsal  artery  of  the 
penis,  as  well  as  the  Cowper's  glands  and  the  membra- 
nous urethra.  It  is  pierced  by  the  membranous  urethra,  the 
ducts  of  Cowper's  glands,  the  artery  of  the  bulb,  the  dorsal 
artery,  vein,  and  nerve  of  the  penis. 

DISSECTION. 

Fill  the  rectum  with  oakum  and  take  two  or  three  stitches  in  the  anus. 

Incisions.  — {i)  In  the  median  line  from  the  perineoscrotal  junction  (base 
of  the  scrotum)  to  the  tip  of  the  coccyx,  cutting  close  to  the  anus  upon  either 
side. 

(2)  Make  an  incision  at  the  anterior  and  posterior  end  of  No.  I,  about 
three  inches  transversely  outward  toward  the  right  and  left.  Do  not  cut  across 
the  base  of  these  flaps,  nor  make  any  other  transverse  incisions. 

Reflect  the  integument  in  the  form  of  two  large  flaps.  In  doing  so  be  care- 
ful not  to  cut  away  the  external  sphincter  of  the  anus,  which  lies  close  to  the 
skin.  Notice  that  while  the  skin  is  thick  in  the  other  parts  of  the  perineum, 
about  the  anus  it  is  very  thin,  and  puckered  into  radiating  lines  by  the  contrac- 
tion of  the  external  sphincter. 

The  Superficial  Fascia.      Diag.  28. 

This  consists  of  two  layers  : — 

{a)  A  subcutaneous  layer  which  varies  in  thickness  ac- 
cording to  the  amount  of  adipose  tissue  present.  When 
this  is  carefully  scraped  away  a  well-marked  but  thin  layer 
of  fascia  is  seen  covering  the  deeper  parts.  This  is  the 
second  layer  of  the  superficial  fascia,  and  is  called  the  peri- 
neal fascia,  or  fascia  of  Colles. 

{i>)  The  perineal  fascia,    fascia   of  Colles,  the    deep 


Fig.  82.  Dissection  of  the  Male  Perineum.  Perineal  triangle  and  con- 
tents.— I,  Corpus  spongiosum.  2,  Accelerator  urinae  (bulhocavernosus).  3,  Crus 
penis  (origin  of  the  corpus  cavernosus).  4,  Erector  penis  (ischiocavernosus).  5,  In- 
ferior pudendal  nerve.  6,  Transversus  perineae  muscle  (superficial).  7,  Transverse 
perineal  artery.  S,  Tuberosity  of  the  ischium.  9,  Gluteus  maximus.  10,  Superficial 
perineal  artery.  11,  Superficial  perineal  nerves.  12,  Tendinous  centre  of  perineum. 
13,  Anus.  14,  Fourth  sacral  nerve.  15,  Tip  of  coccyx.  16,  Sphincter  ani.  17,  Ischio- 
rectal fossa  and  anal  fascia. 


406  A  MANUAL  OF  ANA  TOMY. 

layer  of  the  superficial  fascia.  All  these  terms  are  applied 
to  the  membranous  lamina  of  the  superficial  fascia,  which 
covers  over  the  structures  forming,  and  contained  within, 
the  perineal  triangle.  It  is  attached  behind  to  the  base  of 
the  triangular  ligament,  curving  backward  over  the  trans- 
verse perinei  muscle  to  do  so  ;  laterally,  to  the  inner  margin 
of  the  rami  of  the  ischium  and  pubes  external  to  the 
attachment  of  the  superficial  layer  of  the  triangular  liga- 
ment. Forward,  it  passes  over  the  bulb  of  the  penis  into 
the  scrotum,  where  it  receives  a  reinforcement  of  involun- 
tary muscular  fibres,  and  is  called  the  dartos  of  the  scrotum 
(it  is  also  continuous  with  the  dartos  of  the  penis  or  labium 
majus).  After  leaving  the  scrotum  (and  penis  or  labium 
majus)  it  passes  upward  to  become  continuous  with  the 
deep  layer  of  the  superficial  (Scarpa's)  fascia  of  the  abdo- 
men over  the  spermatic  cord  (round  ligament)  at  the  exter- 
nal abdominal  ring. 

The  perineal  fascia,  after  surrounding  the  scrotum  and 
penis  (as  the  dartos),  becomes  attached  to  the  front  of  the 
symphysis  pubis  as  explained  on  page  .438,  forming  the 
suspensory  lig-ament  of  the  penis,  or  clitoris. 

The  Anus.      Figs.  82,  85. 

The  anus  is  the  opening  of  the  bowel  externally.  The 
lower  part  of  the  rectum  and  the  anus  is  surrounded  by 
circular  muscle  fibres,  the  external  sphincter,  that  wrinkles 
the  skin  into  radiating  lines.      For  this  muscle  see  below. 

The  Inferior  Pudendal  Nerve,  or  Nerve  of  Soemmering. 
Fig.  82. 
This  nerve  is  a  branch  from  the  small  sciatic  under  the 
gluteus  maximus  ;  it  winds  forward  around  the  tuberosity 
of  the  ischium,  perforates  the  deep  layer  of  the  superficial 
fascia  about  an  inch  external  to  the  tuberosity,  passes  for- 


THE  PERINEUM,  MALE.  407 

ward  and  inward  to  the  scrotum,  which  it  supplies.  It  also 
supplies  the  integument  of  the  inner  and  upper  part  of  the 
thigh. 

In  the  female  it  is  distributed  to  the  labium  majus. 

Sphincter  Ani  Externus.      Figs.  82,  '^},. 

Origin. — From  the  tip  of  the  coccyx. 

Insertion. — Into  the  tendinous  centre  of  the  perineum. 

It  is  a  broad,  though  thin,  muscle  which  encircles  the 
anus,  and  by  its  contraction  firmly  closes  it. 

Nerve  Supply. — The  inferior  hemorrhoidal,  from  pudic, 
and  the  fourth  sacral. 

Action. — To  close  the  anus. 

DISSECTION. 
Carefully  pick    out  the   fat   filling  the  posterior   half   of   the   perineum, 
demonstrate  the  boundaries  of  the  fossa  exposed  and  the  vessels  and  nerves 
crossing  it. 

The  Ischiorectal  Fossa.      Fig.  82. 

The  posterior  portion  of  the  perineum. 

This  fossa  is  of  an  irregular  prismatic  shape.  Its  outer 
wall  is  (approximately)  vertical  and  is  formed  by  the  lower 
portion  of  the  obturator  fascia.  Its  inner  wall  is  formed  by 
the  anal  fascia  backed  by  the  levator  ani  and  coccygeus 
muscles  and  the  external  sphincter  of  the  anus,  with  the 
tendinous  centre  of  the  perineum  in  front  and  the  tip  of  the 
coccyx  behind.  In  front,  the  fossa  is  limited  by  the  junc- 
tion of  the  perineal  fascia  and  the  superficial  and  deep 
layers  of  the  triangular  ligament  and  the  anal  fascia  ;  be- 
hind, by  the  margin  of  the  gluteus  maximus  muscle,  the 
great  sacrosciatic  ligament,  and  the  junction  of  the  obtura- 
tor and  anal  fasciae.  The  contents  of  the  fossa  :  Adipose 
tissue,  inferior  hemorrhoidal  arteries,  vessels,  and  nerves. 


408  A  MANUAL  OF  ANA  TOMY. 

The  Hemorrhoidal  Plexus. 

This  venous  plexus  begins  around  the  anus  and  extends 
upward  upon  the  rectum.  It  empties  the  blood  by  the  in- 
ferior hemorrhoidal  vein  into  the  internal  pudic  vein ;  by 
the  middle,  into  the  internal  iliac  and  superior  hemor- 
rhoidal ;  and  by  the  superior,  into  the  inferior  mesenteric, 
which  opens  finally  into  the  portal  vein.  This  establishes 
a  free  venous  communication  from  the  anus  to  the  portal 
vein,  and  so  to  the  liver.  There  are  no  valves  in  these 
veins,  so  the  blood  can  be  dammed  back  from  the  liver  or 
from  the  heart. 

The  Inferior  Hemorrhoidal  Artery.      See  page  412. 

The  Inferior  Hemorrhoidal  Nerve.     See  page  413. 


DISSECTION. 

Carefully  divide  the  perineal  fascia  along  the  median  line  and  across  its 
posterior  attachment  and  reflect  the  two  portions.  If  the  fascia  has  been  par- 
tially destroyed  in  the  dissection  remove  any  parts  left  and  complete  the  clean- 
ing of  the  structures  forming  and  contained  within  the  perineal  triangle. 

The  Perineal  Triangle 

Is  formed    by  the    erector  penis,    accelerator    urinas,    and 
transversus  perineae  muscles. 

It  contains  the  superficial  and  transverse  perineal  vessels 
and  nerves. 

Erector  Penis.      (^Ischiocavei-nosiis.)     Fig.  82. 

Origin. — From  the  inner  surface  of  the  tuberosit}'  and 
ramus  of  the  ischium. 

Insertion. — Into  the  outer  and  under  surface  of  the  crus 
penis,  and  by  a  small  slip  around  the  crus  penis,  to  pass 
over  the  dorsal  vein  of  the  penis  (situated  posterior  to  the 
anterior  slip  of  the  accelerator  urinae).     This  small  slip  is 


i17  .18 

Fig.  83.  Dissection  of  the  Perineum,  Muscles  of  the  Triangle  Removed 
AND  the  Crura  Turned  to  One  Side. — i,  Corpus  spongiosum.  2,  Corpus  caver- 
nosum.  The  crus  is  cut  away  from  its  attachment  and  turned  to  the  side.  3,  Bulb  of 
the  corpus  spongiosum.  4,  Arterial  branch  to  the  corpus  spongiosum.  5,  Artery  of 
the  bulb.  6,  Internal  pudic  artery.  7,  Tuberosity  of  the  ischium.  8,  Dorsal  artery  of 
the  penis.  9,  Artery  to  the  corpus  cavernosum.  10,  Fascia  lata.  11,  Internal  pudic 
artery.  12,  Compressor  urethrse  muscle  (the  deep  transversus  perineae).  This  muscle 
is  thin  and  not  easily  demonstrated  in  a  photograph.  13,  The  superficial  perineal 
nerves  turned  outward.  14,  Inferior  hemorrhoidal  vessels  and  nerve.  15,  Levator 
ani  muscle.     16,  Sphincter  ani.     17,  Anus.    18,  Gluteus  maximus. 


410  A  MANUAL   OF  ANATOMY. 

not  constant  in  man  ;  it  is  named,  from  its  action,  the  com- 
pressor venae  dorsalis  penis. 

Nerve  Supply. — Perineal. 

Action. — To  compress  the  dorsal  vein  of  the  penis  (by 
the  small  slip  mentioned  above)  and  so  produce  erection 
of  the  penis.  The  main  part  of  the  muscle  compresses 
the  crus  penis,  and  so  aids  erection  and  maintains  the  penis 
erect  after  it  becomes  engorged. 

Transversus  Perinsei.  (^Superficial  transversiis  periiicei.) 
Fig.  82. 

Origin. — From  the  inner  surface  of  the  tuberosity  of  the 
ischium. 

Insertion. — Into  the  tendinous  centre  of  the  perineum. 

Nerve  Supply. — Superficial  perineal. 

Action. — To  fix  the  tendinous  centre,  aid  in  supporting 
the  pelvic  floor. 

Accelerator  Urinse.     {Bzilbocavernostis.)     Fig.  82. 

Origin. — From  the  median  raphe,  reaching  from  the 
tendinous  centre  of  the  perineum  forward  upon  the  bulb  of 
the  penis  to  opposite  the  lower  border  of  the  symphysis. 

Insertion.— \\\  three  portions  :  ( i )  A  small  set  of  fibres 
anteriorly,  which  surround  the  corpora  cavernosa  (and,  of 
course,  the  corpus  spongiosum)  to  be  inserted  upon  the 
dorsum  of  the  penis  above  (or  over)  the  dorsal  vein  of  the 
penis.  (2)  A  middle  set,  the  most  of  the  muscle,  which 
passes  forward  around  the  corpus  spongiosum  (and  so  be- 
tween it  and  the  corpora  cavernosa)  to  the  dorsum  of  the 
corpus  spongiosum.  (3)  A  third  set  posteriorly,  also 
small,  which  surrounds  the  bulb  of  the  penis  behind  the 
membranous  urethra,  and  is  inserted  into  the  dorsum  of 
the  bulb  and  the  superficial  layer  of  the  triangular  ligament 
close  to  the  exit  of  the  urethra. 


THE  PERINEUM,  MALE.  411 

Nerve  Supply. — Perineal. 

Action. — The  anterior  portion  compresses  the  dorsal  vein 
of  the  penis  and  so  produces  erection  of  the  organ.  The 
middle  portion  compresses  the  bulb  and  its  vessels  and  so 
aids  the  action  of  the  anterior  portion.  The  posterior  part 
compresses  the  membranous  urethra  and  expels  its  contents 
(urine  or  semen).  This  last  action  is  continued  by  the  two 
other  portions  of  the  muscle,  acting  peristaltically  from  be- 
hind forward. 

The  Internal  Pudic  Artery.      Figs.  82,  83,  1 12,   i  14. 

This  is  the  smaller  branch  of  the  bifurcation  of  the 
anterior  trunk  of  the  internal  iliac  artery,  the  larger  being 
the  sciatic.  It  leaves  the  pelvic  cavity  with  the  sciatic  be- 
tween the  coccygeus  and  pyriformis  muscles,  through  the 
greater  sacrosciatic  foramen,  curves  around  the  base  of  the 
spine  of  the  ischium,  having  the  internal  pudic  nerve  on  its 
internal  and  the  nerve  to  the  obturator  internus  muscle  on 
its  external  side  ;  then  re-enters  the  pelvic  cavity  (ischio- 
rectal fossa)  through  the  lesser  sacrosciatic  foramen  ;  the 
artery  now  runs  forward  along  the  outer  surface  of  the 
ischiorectal  fossa,  being  contained  in  a  canal  (Alcock's) 
formed  by  the  separation  of  the  obturator  fascia.  In  this 
part  of  its  course  the  artery  is  situated  about  an  inch 
above  the  lower  margin  of  the  tuberosity  of  the  ischium, 
and  is  accompanied  by  the  pudic  nerve,  which  divides  soon 
after  entering  the  ischiorectal  fossa  into  the  superficial  peri- 
neal nerve  and  the  dorsal  nerve  of  the  penis  ;  the  former 
nerve  is  below  and  the  latter  above  the  artery  (subject 
standing). 

The  artery  continues  forward,  perforates  the  posterior 
layer  of  the  triangular  ligament  close  to  the  ramus  of  the 
ischium,  along  which  it  extends  between  the  two  layers  of 


412  A  MANUAL  OF  ANA  TO  MY. 

the  triangular  ligament  and  within  the  substance  of  the 
compressor  urinae  muscle  to  the  anterior  part  of  the  space, 
where  it  divides  into  the  artery  of  the  crus  and  the  dorsal 
artery  of  the  penis.  The  latter  continues  the  course  of 
the  internal  pudic  forward  and  upward,  perforating  the 
superficial  layer  of  the  triangular  ligament  close  to  the 
opening  for  the  dorsal  vein  of  the  penis,  then  passes  between 
the  crura  and  symphysis  pubis  and  through  the  suspensory 
ligament  of  the  penis  to  the  dorsal  surface  of  that  organ, 
where  it  lies  external  to  the  dorsal  vein,  which  is  centrally 
placed.  It  continues  along  the  dorsum  of  the  penis  to  the 
glans,  where  it  ends  by  breaking  up  into  a  coronary  anasto- 
mosis. It  also  sends  branches  to  the  prepuce.  The 
dorsal  artery  is  accompanied  in  its  course  by  the  nerve  of 
the  same  name  which  is  placed  outside  of  the  artery. 
Brandies  of  the  Internal  Pudic. 

( 1 )  The  inferior  hemorrhoidal  branch  (or  branches,  i 
to  3)  is  given  off  as  the  pudic  enters  the  rectovesical  fossa. 
It  passes  through  the  fat,  filling  the  fossa,  to  the  rectum 
and  anus.  Above,  it  anastomoses  with  the  middle  hemor- 
rhoidal of  the  anterior  division  of  the  internal  iliac.  (Con- 
sult the  intestinal  anastomoses.) 

(2)  The  superficial  perineal  artery  is  given  off  at  the 
base  of  the  triangular  ligament,  perforates  the  perineal 
fascia,  crosses  over  or  behind  the  transverse  perineal  muscle, 
extends  forward  between  the  erector  and  crus  penis  and  the 
accelerator  urinae  muscles,  to  the  base  of  the  scrotum, 
where  it  ends  in  supplying  the  superficial  parts  of  that 
structure.  It  gives  off  the  transverse  perineal  artery  to  the 
muscle  of  that  name,  besides  supplying  the  adjacent  parts. 

(3)  The  artery  to  the  bulb.  This  is  a  considerable 
artery  which  arises  from  the  internal  pudic  within  the  space 
between  the  layers  of  the  triangular  ligament.      Its  course 


THE  PERINEUM,  MALE.  413 

is  forward  and  inward  through  the  compressor  urethrae 
muscle.  When  near  the  middle  line  it  penetrates  the  super- 
ficial layer  of  the  triangular  ligament  and  enters  the  bulb. 
It  supplies  Cowper's  glands,  the  membranous  urethra,  the 
bulb,  and  the  corpus  spongiosum. 

(4)  The  artery  to  the  crus.  The  larger  of  the  terminal 
branches  of  the  internal  pudic.  This  perforates  the  anterior 
layer  of  the  triangular  ligament,  enters  the  crus  penis 
(corpus  cavernosum),  through  the  centre  of  which  it  passes 
to  its  anterior  extremity,  giving  off  numerous  branches  in 
its  course  to  this  body. 

(5)  The  dorsal  artery  of  the  penis.  The  smaller 
branch  of  the  bifurcation  of  the  internal  pudic.  For  its 
course,  see  above. 

The  Internal  Pudic  Vein. 

This  begins  as  a  branch  from  the  corpus  cavernosum, 
receives  a  communicating  branch  from  the  dorsal  vein  of 
the  penis,  retraces  the  course  of  the  internal  pudic  artery, 
receiving  in  its  course  branches  corresponding  to  the 
branches  of  the  artery,  and  finally  empties  into  the  begin- 
ning of  the  internal  iliac  vein. 

The  Internal  Pudic  Nerve.      Figs.  82,  83,  112,  114. 

This  is  found  in  the  dissection  of  the  perineum,  as  it 
enters  the  ischiorectal  fossa  through  the  lesser  sacrosciatic 
foramen  along  with  the  internal  pudic  artery.  It  courses 
along  the  side  of  this  fossa  with  the  artery,  being  contained 
in  a  canal  in  the  obturator  fascia,  and  divides  into  the 
perineal  and  dorsal  nerve  of  the  penis  (clitoris).  Before 
this  division  the  nerve  gives  off  the  (i)  inferior  hemor- 
rhoidal branch,  which  passes  inward  to  the  external  sphinc- 
ter of  the  anus  and  the  intesfument  over  it. 


414  A   MANUAL   OF  ANATOMY. 

(2)  The  perineal  nerve.  This  lies  below  the  artery 
(subject  standing).  It  penetrates  the  perineal  fascia  close 
to  the  base  of  the  triangular  ligament,  divides  into  two 
branches,  the  posterior  or  external  and  the  internal  or  ante- 
rior. These  branches  pass  through  the  perineal  triangle 
and  terminate  in  the  scrotum  (female,  the  labium  majus). 
From  this  nerve  muscular  branches  pass  to  the  transversus 
perinaei,  accelerator  urinae  (sphincter  vaginae),  erector  penis 
(clitoris),  and  filaments  also  pass  to  the  compressor  urethrae, 
bulb,  and  mucous  membrane  of  the  urethra. 

(3)  The  dorsal  nerve  of  the  penis  lies  first  above  the 
internal  pudic  artery,  continues  with  the  artery  into  the 
triangular  space,  crossing  the  artery  to  get  below  it.  It 
leaves  the  triangular  space  with  the  dorsal  artery  of  the 
penis,  being  situated  at  the  outer  side  of  the  artery,  and 
terminates  in  branches  to  the  glans.  For  the  course  of 
the  artery  see  above. 

The  nerve  supplies  in  its  course  branches  to  the  corpus 
cavernosum,  glans,  and  integument  of  penis. 

In  the  female  the  nerve  is  smaller,  but  takes  a  similar 
course  and  distribution. 

DISSECTION. 
Remove  the  erector  penis,  accelerator  urinse,  and  transversus  perinese  mus- 
cles.     Clean  the  bulb    (corpus   spongiosum),  crura  (corpora   cavernosa),   and 
the  anterior  layer  of  the  triangular  ligament. 

The  Corpus  Spongiosum.  (Is  described  here,  but  see 
page  440  for  dissection  of  penis.)      Fig.  83. 

This  is  a  cylindrical  tube  of  fascia  containing  erectile 
tissue,  and  traversed  through  its  centre  by  the  urethra.  It 
is  placed  below  and  between  the  two  crura,  to  which  it  is 
firmly  bound  by  the  sheath  of  the  penis. 

It  is  dilated  at  each  end  ;  the  anterior  dilatation  is  called 


THE  PERINEUM,  MALE.  415 

the  glans.  (See  dissection,  page  440.)  It  is  a  heart- 
shaped  enlargement,  which  spreads  out  laterally  and  back- 
ward beyond  the  crura,  which  terminate  within  it.  The 
margin  of  the  glans  is  called  the  corona  g-landis,  and  the 
constricted  portion  behind  it  the  neck  of  the  penis.  The 
glans  shows  a  vertical  slit  at  its  extreme  end,  the  external 
urinary  meatus.  The  posterior  dilatation  is  named  the 
bulb.  It  is  about  one  and  one-half  inches  long,  and  pro- 
jects a  little  beyond  the  membranous  urethra,  which  enters 
this  portion  of  the  corpus  spongiosum.  The  bulb  lies  upon 
(really  below)  the  anterior  triangular  ligament,  being  sur- 
rounded by  the  accelerator  urinae  muscle  and  covered  by 
the  perineal  fascia. 

The  portion  of  the  corpus  spongiosum  between  the  glans 
and  bulb  is  called  the  body.  Through  its  centre  the  ure- 
thra passes,  the  space  between  the  urethra  and  sheath  of 
the  corpus  being  filled  with  erectile  tissue.  The  corpora 
cavernosa  and  the  corpus  spongiosum  are  bound  together 
by  the  elastic  fascial  sheath  of  the  penis,  which  extends 
from  the  root  of  the  penis  to  the  glans.  Within  this  elastic 
sheath  are  found  the  deep  dorsal  nerves,  arteries,  and 
vein  of  the  penis,  while  external  to  it  are  the  superficial 
dorsal  vessels  and  nerves.  The  former  arteries  and  nerves 
are  from  the  internal  pudic  artery  and  nerve  ;  the  vein  emp- 
ties into  the  prostatic  sinus  plexus.  The  latter  vessels  are 
from  the  external  superficial  and  deep  pudic  arteries  ;  the 
veins  open  into  their  venje  comites,  and  the  nerves  are 
branches  of  the  iliohypogastric.      See  page  440. 

Beneath  the  skin  and  external  to  the  fibrous  sheath  lies 
a  membranous  layer  composed  of  fibrous  and  muscular 
tissue — the  dartos — which  is  continuous  with  the  similar 
layer  of  the  scrotum  and  the  fascia  of  Scarpa.  See  pages 
404,438. 


416  A  MANUAL   OF  ANA  TOMY. 

The  Corpora  Cavernosa.      Figs.  82,  83. 

Each  corpus  consists  of  a  cylindrical  tube  of  dense  fas- 
cia (tunica  albuginea)  containing  erectile  tissue.  It  is 
pointed  at  both  ends,  the  anterior  being  short  and  imbedded 
in  the  substance  of  the  glans,  the  posterior  longer,  more 
slender,  and  tapering,  and  being  attached  firmly  to  the  inner 
margin  of  the  ramus  of  the  pubes  and  ischium.  This  por- 
tion of  the  corpus  cavernosum  is  called  the  crus  penis. 

The  artery  of  the  crus  enters  it  close  to  its  bony  attach- 
ment, and  runs  through  its  centre  to  the  anterior  extremity, 
giving  off  in  its  course  numerous  branches  to  the  erectile 
tissue.  The  vein  of  the  crus  emerges  where  the  artery 
enters,  and  is  continued  posteriorly  under  the  name  of  the 

Internal  Piidic  Vein,  q.  v.,  page  413. 

The  two  crura  are  separated  below,  where  they  are 
fastened  to  the  pubic  arch,  and  at  their  anterior  extremity, 
where  they  terminate  in  the  glans,  but  the  intervening 
portion  is  firmly  united  by  an  envelope  of  fascia  in  addition 
to  their  own  proper  sheaths. 

When  the  crura  are  cut  apart  the  line  of  division  shows 
numerous  transverse  striations,  called  the  septum  pec- 
tiniforme. 

Anterior  Portion  of  the  Triangular  Ligament.      See  page 

403- 

DISSECTION. 
Remove  what  is  left  of  the  anterior  layer  of  the  triangular  ligament.     Ex- 
pose the  compressor  urethrse,  Cowper's  glands,  the  deeper  branches  of  the 
internal  pudic  artery  and  nerve. 

Compressor  Urethrae.     [Deep   Transverse  Perincei.)     Fig. 

83- 
Origin. — From   the  inner    margin    of   the   rami    of  the 

ischium  and  pubes. 

Insertion. — Into  a  median  raphe. 


THE  PERINEUM,  MALE.  417 

Neme  Supply. — Dorsal  nerve  of  the  penis. 

Action. — To  compress  the  membranous  urethra,  which 
it  surrounds,  expelling  its  contents  (urine  or  semen).  To 
aid  erection  by  compressing  the  emergent  veins  of  the  penis. 
To  compress  Cowper's  glands  and  so  force  out  their  secre- 
tion. This  may  be  independent  of  the  emission  of  semen 
or  in  connection  with  that  act. 

Ccwper's  Glands.      Diag.  28. 

These  are  two  glands  about  as  large  as  small  peas, 
situated  between  the  two  layers  of  the  triangular  ligament, 
close  to  and  behind  the  membranous  urethra,  and  under 
(above)  the  bulb  of  the  penis. 

The  duct  of  a  gland  is  about  an  inch  long.  It  pierces 
the  anterior  layer  of  the  triangular  ligament,  the  corpus 
spongiosum,  and  opens  into  the  floor  of  the  urethra  (bul- 
bous portion). 

DISSECTION. 
Carefully   remove   the    compressor   urethrse   muscle    and   the   nerve    and 
artery  and  their  branches. 

Remove  the  hemorrhoidal  vessels  and  nerves. 
Section  a  portion  of  the  gluteus  maximus. 

The  Posterior  Layer  of  the  Triangular  Ligament.  See 
page  402. 

TJie  Anal  Fascia.     See  page  402. 

DISSECTION. 
Remove  the  posterior  layer  of  the  triangular  ligament  and  the  anal  fascia 
(which  are  continuous,  as  explained). 

Levator  Ani.      Fig.  83. 

Origin. — From  the   inner   surface   of    the   body  of    the 
pubis,  from    the  angle   between   the   obturator  and  recto- 
vesical fascijE — the  so-called  "  white  line  " — and  from  the 
inner  surface  of  the  spine  of  the  ischium. 
27 


418  A  MANUAL  OF  ANATOMY. 

Insertion. — Into  the  tip  of  the  coccyx,  into  the  median 
raphe  extending  from  the  coccyx  to  the  anus,  into  the 
lateral  surfaces  of  the  rectum,  also  into  the  median  raphe 
as  far  forward  as  the  tendinous  centre  of  the  perineum.  In 
the  female  the  anterior  fibres  of  the  muscle  are  attached  to 
the  side  of  the  vagina. 

Nerve  Supply. — Inferior  hemorrhoidal,  fourth  and  fifth 
sacral. 

Action. — To  elevate  the  pelvic  floor  and  rectum,  prostate 
(vagina)  and  bladder.  To  diminish  the  pelvic  cavity,  thus 
compressing  the  abdominal  viscera,  and  aid  in  all  expulsive 
efforts.  The  levator  ani  and  the  coccygeus  have  been 
called  the  pelvic  diaphragm,  as  their  combined  action 
resembles  the  action  of  the  diaphragm. 

Coccygeus. 

Origin. — From  the  inner  surface  of  the  spine  of  the 
ischium. 

Insertion. — Into  the  side  of  the  coccyx  and  the  last  two 
pieces  of  the  sacrum  and  the  lateral  ligaments  connecting 
the  two  bones. 

Nerve  Supply. — Fourth  and  fifth  sacral  and  the  coccygeal. 

Action. — Draws  the  coccyx  forward  and  aids  the  leva- 
tor ani. 

DISSECTION. 

Remove  the  levator  ani,  cutting  it  away  at  its  origin  and  insertion. 

Consult  the  description  of  the  rectovesical  fascia,  page  399. 

Draw  the  rectum  backward,  and  keeping  close  to  it  cut  the  fascia  between 
it  and  the  prostate  and  bladder  until  the  rectovesical  fold  of  peritoneum  is 
reached.     Clean  the  prostate  and  base  of  bladder. 

The  Prostatic  Plexus. 

This  is  a  plexus  situated  within  the  capsule  of  the  pros- 
tate and  between  the  rectovesical  fascia  and  the  neck  of  the 
bladder. 


Fig.  84.  Dissection  of  the  Perineum.  The  Prostate  and  Base  of  the 
Bladder.— I,  Tube  in  the  urethra.  2,  The  urethra.  3,  Dorsal  vein  of  the  penis 
4,  Prostate  gland.  5,  Notch  in  the  prostate  where  the  6,  Ejaculatorv  duct  enters. 
7,  Dorsal  nerve  of  the  penis.  8,  Internal  pudic  arterv.  9,  Tuberositv  of  the  ischium. 
10,  A  seminal  vesicle.  11,  The  vas  deferens.  12,  The  external  trigone  of  the  bladder. 
13,  Point  where  the  peritoneum  is  reflected  from  the  bladder  to  the  rectum,  recto- 
vesical pouch.  14,  Great  sacrosciatic  ligament.  15,  Gluteus  maximus  muscle. 
16,  Coccyx.     17,  Rectum. 


420  A  MANUAL   OF  ANATOMY. 

It  receives  the  two  veins  of  divisions  of  the  dorsal  vein  of 
the  penis,  the  veins  of  the  prostate  and  bladder,  communi- 
cates with  the  hemorrhoidal  plexus,  and  empties  by  a  right 
and  left  branch  into  the  corresponding  internal  iliac  vein. 

The  Vesical  Plexus 

Is  formed  by  the  veins  which  surround  the  bladder  and  at 

its  base  empty  into  the  prostatic  plexus. 

In  the  female,  the  vaginal  plexus  surrounds  the  vagina 
and  opens  into  the  hemorrhoidal  and  vesical  plexuses. 
The  uterine  plexus  terminates  in  the  ovarian  veins. 

Base  of  the  Bladder.     See  page  537. 

The  external  trig-one  (Fig.  84)  is  the  surface  of  the  bladder 
included  between  the  diverging  vasa  deferentia  and  the  peri- 
toneal reflection  from  the  bladder  to  the  rectum,  which  is  from 
one  to  one  and  one-half  inches  from  the  base  of  the  prostate. 

The  Seminal  Vesicles.      Fig.  84. 

These  are  two  in  number,  two  inches  long,  one-half  inch 
wide,  one-quarter  inch  thick,  situated  outside  the  vas 
deferens,  one  and  one-quarter  inches  above,  and,  like  the 
vas,  inclining  downward  and  inward  to  the  prostatic  notch 
to  empty  into  the  common  duct.  Their  function  is  the 
storage  of  the  seminal  fluid. 

Relations. — Behind  is  the  rectum  ;  in  front,  the  bladder 
and  termination  of  the  ureters  ;  internally,  the  vas  deferens  ; 
below,  the  prostate.  They  are  enclosed  in  a  capsule  from 
the  rectovesical  fascia.  When  unraveled  each  vesicle  is 
found  to  consist  of  a  single  tube  about  four  inches  long, 
with  numerous  blind  outgrowths. 

Vas  Deferens.     See  page  542. 

The  Prostate.      Fig.  84.      Diags.  27,  28. 

This  is  a  libromuscular  gland  surrounding  the  neck  of 
the  bladder  and  the  beeinnine  of  the  urethra.      It  is  heart- 


THE  PERINEUM,  MALE.  421 

shaped,  one  and  one-half  inches  across  the  base  and  one 
and  one-quarter  inches  in  vertical  extent,  placed  with  its 
base  uppermost  and  the  apex  below.  There  is  a  notch  at 
the  base  dividing  the  gland  into  two  lobes.  Into  this  notch 
the  vasa  deferentia  and  seminal  vesicles  converge  to  unite 
into  the  common  ejaculatory  ducts  which  traverse  the 
prostate  downward  and  forward  to  open  into  the  floor  of 
the  prostatic  urethra.  The  gland  is  enclosed  in  a  capsule 
derived  from  the  rectovesical  fascia,  upon  which  it  rests. 
At  the  apex  of  the  gland,  at  the  place  where  the  urethra 
issues,  the  fibres  of  the  levator  ani  muscle  are  wanting  (the 
muscle  being  behind  the  gland),  and  at  this  point  the  recto- 
vesical fascia  becomes  continuous  with  the  deep  layer  of 
the  triangular  ligament. 

Relations. — Above  :  The  bladder,  vasa  deferentia,  seminal 
vesicles.  Behind  :  Rectum  separated  only  by  a  thin  layer 
of  rectovesical  fascia.  Below  :  The  rectovesical  fascia  and 
deep  layer  of  the  triangular  ligament.  In  front :  Pubo- 
prostatic ligaments.  Laterally  :  Capsule  derived  from  the 
rectovesical  fascia,  and  separating  it  from  the  levator  ani 
muscle.  The  prostatic  venous  plexus  encloses  the  gland, 
being  between  it  and  its  capsule.  Into  the  front  of  the 
plexus  the  deep  vein  of  the  penis  empties. 

The  Lower  Portion  of  the  Rectum.  For  the  upper 
part,  see  page  504.  Fig.  84.  Diag.  28. 
The  lower  portion  of  the  rectum  extends  from  the  tip  of 
the  coccyx  to  the  anus,  a  distance  of  one  and  one-half 
inches.  This  part  of  the  rectum  curves  downward  and 
backward  ;  consequently,  in  introducing  a  tube  into  the  rec- 
tum it  should  first  be  pointed  forward  and  upward  or  toward 
the  umbilicus,  then  it  may  be  carried  backward  toward  the 
sacrum.      In  children  this  precaution  should  be  followed. 


422 


A  MANUAL   OF  ANATOMY. 


The  second  part  of  the  rectum  is  enclosed  by  the  in- 
ternal sphincter,  which  is  only  an  increase  in  the  circular 
muscular  fibres,  and  has  the  levator  ani  supporting  it  at  its 
sides.     Fig.  82. 

In  fi-ont,  is  the  lower  part  of  the  prostate,  the  base  of 
the  triangular  ligaments,  the  transverse  peroneal  muscles. 


THE  PERINEUM,  Female. 

The  Landmarks. 

Consult  the  male  perineum  for  the  boundaries  of  the 
pelvic  outlet,  page  397.  Notice  the  various  differences 
between  the  male  and  female  pelvic  outlet.  The  pubic 
arch  in  the  female  is  wider  than  in  the  male,  and  the 
tuberosities  of  the  ischium  are  farther  apart. 

Comparative  measurements  of  the  male  and  female 
pelvis  (internal)  : — 

The  female  pelvis  (Grandin  and  Jarman,  "  Obstetric 
Surgery  "). 


Diameters. 
Transverse,  . 
Oblique,  .  . 
Conjugate,  .    . 


Brim. 
■  5  in- 

.  4X  to  5  in. 
•  4X  to  4)4  in. 


The  male  pelvis. 

Diameters.  Brim. 

Transverse,  .  .  4^  in. 
Oblique,  ....  4^  in. 
Conjugate,  .    .    .    .  4  in. 


Cavity. 
5  to  SX  in. 
5  to  5X  in. 
A%  in. 


Cavity. 
Ayi  in. 
A-}4  in. 
4X  in. 


Outlet. 
4X  in. 
AH  in. 
5  in. 


Outlet. 
ZVz  in. 
4  in. 
3X  in. 


The  External  Genitals.      Fig.  85. 

These  should  be  carefully  identified.      In  comparing  the 
following  descriptions  with  other  text-books  many  smaller 


THE  PERINEUM,  FEMALE.  423 

differences  will  be  marked  ;  these  differences  are  believed  to 
be  justified  by  a  careful  examination  of  the  subject  (living 
as  well  as  dead)  and  from  the  conclusions  of  other  ob- 
servers. 

The  Vulva. — "  The  external  genitals  of  the  female,  ex- 
cepting the  mons  veneris  "  ("  Foster's  Dictionary  "). 

The  Pudendum. — "  The  external  genitals  (especially 
those  of  the  female,  including  the  vulva  and  mons  veneris  ") 
(same).  Quain  uses  the  terms  synonymously  to  include 
the  mons  veneris,  labia  majora  and  minora,  the  hymen  or 
its  remains,  the  clitoris,  and  meatus  urinarius. 

(i)  The  Mons  Veneris. — The  fatty  elevation  covering 
the  pubes. 

(2)  The  Labia  Majora. — The  homologue  of  the  scrotum, 
remaining  permanently  cleft  along  the  middle  line  (this 
cleft  is  the  rima  pudendi,  or  genitalis).  The  labia  majora 
form  two  elevations  reaching  from  the  mons  veneris  in  front 
toward  the  tendinous  centre  of  the  perineum.  The  posterior 
junction  of  these  labia  is  said  to  form  the  posterior  com- 
missure, but  an  examination  of  the  subject  (living  and  dead) 
will  convince  any  one  that  they  do  not  unite  in  this  manner, 
but  flatten  out  into  the  smooth  covering  of  the  perineum. 

(3)  The  Labia  Minora. — Related  morphologically  to  the 
integument  and  foreskin  of  the  penis.  They  are  two  folds 
of  integument  (the  word  is  used  advisedly)  smaller  than 
the  labia  majora,  located  internal  to  the  labia  majora,  by 
which  they  are  usually  concealed  from  sight.  They  are 
joined  in  front  over  the  cUtoris,  forming  its  prepuce,  and 
behind  by  the  fourchette,  a  thin  fold  of  membrane. 

(4)  The  Clitoris. — Akin  to  the  penis  of  the  male.  Its 
blunt  extremity  is  called  the  glans  clitoridis,  and  is  cov- 
ered by  the  prepuce,  formed  by  the  labia  minora. 


424  A  MANUAL   OF  ANATOMY. 

(5)  The  Pourchette. — The  narrow  fold  or  band  of 
membrane  (integument)  which  joins  the  labia  minora  pos- 
teriorly (usually  torn  in  childbirth). 

(6)  The  Vestibule. — This  is  the  median  gutter  which 
extends  from  the  clitoris  in  front  to  the  hymen  or  its  re- 
mains behind,  and  is  bounded  laterally  by  the  labia  minora. 
Into  it  opens  the  meatus  urinarius. 

(7)  The  Hymen. — An  irregular,  ring-like  fold  of  mem- 
brane (probably  integument),  which  surrounds  the  entrance 
to  the  vagina.  It  is  really  external  to  and  below  the 
vagina  (D.  S.  Lamb).  Torn  in  childbirth  always.  The 
numerous  small  nodules  remaining  to  mark  the  site  of  the 
hymen  in  women  who  have  had  children  are  called  the 
carunculee  myrtiformes. 

(8)  The  Meatus  Urinarius. — The  external  opening  of 
the  female  urethra  is  in  the  median  line  of  the  vestibule  and 
about  three-fourths  to  one  inch  from  the  clitoris. 

(9)  The  Fossa  Navicularis  is  the  shallow  depression 
between  the  hymen  (internally)  and  the  fourchette  (exter- 
nally.) 

(10)  The  Orifice  of  the  Vagina  lies  in  the  middle  line. 
It  is  narrowed  in  the  virgin  by  the  hymen,  and  surrounded 
in  the  matron  by  the  carunculae  myrtiformes. 

(11)  Opening  of  the  Ducts  of  the  Glands  of  Bar- 
tholin is  on  the  inner  side  of  the  labia  minora,  external  to 
the  hymen,  and  on  a  level  with  the  middle  of  the  vaginal 
orifice. 

The  Anus.     See  page  406. 


DISSECTION. 
Distend  the  vagina  and  rectum  with  oakum,  and  take  several  interrupted 
sutures  in  the  labia  majora  and  the  anus. 


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426  A  MANUAL  OF  ANATOMY. 

Incisions. — (i)  Incise  the  labia  majora  close  to  their  inner  margin  from 
the  mons  veneris  to  the  median  line  of  the  perineum  ;  carry  the  incision 
around  the  anus  to  the  coccyx  behind. 

(2)   Make  the  transverse  incisions  as  indicated  on  page  404. 

Carefully  remove  the  integument,  especially  about  the  labial  margin  and 
around  the  anus. 

The  descriptions  of  the  various  structures  given  under 
the  male  perineum  will  apply  with  a  slight  modification  to 
the  female  parts. 

The  Superficial  Fascia.      See  page  404. 

This  consists  of  the  two  layers,  these  layers  being  pierced 
by  the  vaginal  opening.  The  deep  layer  forms  in  the 
female  an  imperfect  dartos  of  the  labia  majora  as  it  does 
the  dartos  of  the  scrotum  in  the  male. 

Sphincter  Ani  Externus.      See  page  407. 

The  Ischiorectal   Fossa,  situation,  formation,  boundaries, 
and  contents.      See  page  407.      Fig.  86. 

The  Internal  Pudic  Artery.      See  page  411.      Fig.  86. 

In  the  female  there  are  these  variations  :  the  superficial 
perineal  artery  is  larger  than  in  the  male  and  is  distributed 
to  the  labia  majora  and  minora.  The  artery  of  the  bulb 
ends  in  the  bulb  of  the  vestibule,  and  is  smaller  than  in 
the  male.  The  artery  of  the  crus  is  a  small  branch  to  the 
crus  clitoridis. 

The  dorsal  artery  of  the  clitoris  is  much  smaller  than 
the  corresponding  artery  in  the  male. 

The  Internal  Pudic  Nerve.     See  page  413.      Fig.  86. 

In  the  female  the  superficial  perineal  nerves  supply  the 
labia,  the  erector  clitoridis,  the  sphincter  vaginae,  and  the 
compressor  vaginae.  The  dorsal  nerve  of  the  clitoris  is  a 
small  branch  which  supplies  that  organ. 


THE  PERINEUM,  FEMALE.  427 

DISSECTION. 

Remove  the  perineal  fascia  and  dissect  out  the  perineal  triangle.  This 
will  be  more  difficult  to  do  than  in  the  male,  as  the  parts  are  smaller,  the 
sphincter  vagina;  (corresponding  to  the  accelerator  urinje)  imperfectly 
developed  and  perforated  by  the  vaginal  orifice. 

After  careful  dissection,  consult  the  male  perineal  triangle,  page  408. 

Transversus  Perinaei.    Same  as  in  the  male.      See  page 

410. 
The  Erector  Clitoridis.    Smaller,  but  similar  to  the  erector 

penis  in  the  male.      See  page  408. 

The  Sphincter  Vaginae. 

In  the  male  the  accelerator  urinse  or  the  bulbocavernosus, 
page  410.  Originates  from  the  tendinous  centre  of  the 
perineum,  passes  forward  to  the  parts  about  the  clitoris, 
surrounding  the  vagina.  It  is  an  indistinct,  imperfectly- 
developed  plane  of  muscular  fibres. 

DISSECTION. 

Divide  the  transversus  perineoe  and  sphincter  vaginae  muscles  and  reflect 
them.     Cut  away  the  erector  clitoridis. 

Draw  the  clitoris  forward  and  remove  the  mucous  membrane  between  it 
and  the  urethral  orifice. 

The  orifice  of  the  urethra  presents  in  the  middle  line  nearly  midway 
between  the  pubic  arch  and  the  vaginal  orifice. 

The  Bulb  of  the  Vagina,  or  Bulbi  Vestibuli. 

This  is  the  female  representative  of  the  corpus  spongio- 
sum in  the  male.  The  bulb  of  the  vagina  consists  of  two 
portions,  each  about  an  inch  long  and  lying  upon  the  front 
and  sides  of  the  vaginal  opening  and  just  under  the 
sphincter  vaginae  muscle.  The  bulbs  are  connected  in 
front  over  the  meatus  urinarius  by  a  narrow  neck  (pars 
intermedialis  of  Kobelt). 
The  Clitoris.      Figs.  85,  86. 

Morphologically  identical   with  the  male    penis.     It   is 


428  A  MANUAL   OF  ANA  TOMY. 

composed  of  two  small  corpora  cavernosa  attached  simi- 
larly to  the  corpora  cavernosa  in  the  male.  See  page  416. 
The  corpora  cavernosa  converge  from  the  pubic  arch,  unite 
to  form  the  body  of  the  clitoris,  and  terminate  in  a  blunt 
extremity  (different  from  the  male)  which  is  called  the 
glans  clitoridis. 

The  clitoris  is  covered  by  a  modified  integument,  and 
is  suspended  from  the  symphysis  pubis  by  a  small  ligament 
similar  to  the  suspensory  ligament  of  the  penis. 

The  Artery  and.  Nerve  to  the  Bulb.     See  pages  412,  414. 

The  Artery  and  Nerve  to  the  Corpus  Cavernosum  and 
the  Dorsal  Artery  and  Nerve  of  the  Clitoris.     See 

pages  413,  414.      Fig.  %6. 

The  Anterior  Layer  of  the  Triangular  Ligament. 

The  description  on  page  403  will  answer  for  this  struc- 
ture in  the  female,  in  addition  noting  that  it  is  perforated  by 
the  vagina. 

DISSECTION. 
Remove  the  anterior  layer  of  the  triangular  ligament. 

Compressor    Urethree.       Constrictor    Vaginse.      {Deep 
Tra7isversus  PeriiKzi.^ 

The  compressor  urethrae  muscle  occupies  the  same  posi- 
tion in  the  female  that  it  does  in  the  male.  Besides  its 
urethral  function  it  also  constricts  the  vagina.  It  is  not  so 
well  developed  as  in  the  male.      See  page  416. 

Various    small   muscles   are    described   in   this  plane  by 
various  dissectors.    It  is  sufficient  if  the  student  now  recog- 
nizes the  above  muscle. 
The  Grlands  of  Bartholin,     {Cozvpcr'' s  Glands  in  the  male.) 

These  are  two  small  glands  lying  opposite  to  the  posterior 
half  of  the  vaginal  orifice,  just  behind  the  bulbs  of  the 
vagina,  imbedded  within    the  constrictor  vaginae  muscle. 


2  3    4       5 


6  7     8  9  10  111213  14  15 

Fig.  86.  Dissection  of  the  Female  Perineum.— i,  Tube  in  the  ureUira. 
2,  Glaus  clitoridis.  3,  Dorsal  artery  of  the  clitoris.  4,  Dorsal  nerve  of  the  clitoris. 
5,  Corpus  cavernosum.  It  terminates  in  the  crus  clitoridis.  6,  Gluteus  maximus. 
7,  Anterior  vaginal  wall.  8,  Vaginal  orifice.  9,  Anus  (rectum).  10,  Coccyx.  11, 
Superficial  perineal  artery.  12,  Inferior  hemorrhoidal  artery  and  the  ischiorectal 
fossa.     13,  The  internal  pudic  artery.     14,  Tuberosity  of  the  ischium.     15,  Fascia  lata. 


430  A  MANUAL  OF  ANATOMY. 

They  open  by  a  duct,  about  three-fourths  of  an  inch   long, 

opposite  the  middle  of  the  vaginal  opening. 

The  Posterior  Layer  of  the  Triangular  Ligament 

Is  the  same  as  in  the  male  (see  page  402),  besides  being 

pierced  by  the  vagina.     It  is  continuous  with  the  anal  fascia 

covering  the  levator  ani  muscle. 

Levator  Ani  and  Coccygeus  Muscles.     See  pages  417, 

418. 

DISSECTION. 
Draw  the  rectum  backward  and  separate  it  from  the  vagina  until  the  recto- 
vesical fold  of  peritoneum  passing  between  them  is  reached.     Notice  how  far 
this  fold  reaches  downward  into  the  rectum  and  vagina. 

In  like  manner  separate  the  vagina  from  the  urethra  and  base  of  the 
bladder.  Expose  the  ureters,  and  carefully  note  their  position  with  reference 
to  the  uterus,  vagina,  and  bladder. 

The  Rectum.   .  See  page  42 1 . 

For  the  description  of  the  rectovesical  fascia,  see  page  399. 

The  Vagina. 

This  membranous  canal  is  usually  described  as  one  of 
the  parts  of  the  internal  organs  of  generation  of  the  female, 
but  it  properly  belongs  to  the  external  genitals.  It  extends 
from  the  hymen  upward  and  backward  to  enclose  the  lower 
portion  of  the  uterus.  The  angle  of  reflection  from  the 
uterus  is  called  the  fornix.  Its  anterior  wall  is  about  three 
inches  long,  its  posterior,  about  four.  In  the  natural  state 
the  two  walls  are  in  contact  and  the  fissure  between  them  re- 
sembles the  letter  "  H,"  a  long  transverse  limb  and  two 
short  vertical  limbs. 

Relations. — In  front  :  The  urethra,  base  of  bladder,  and 
ureters,  which  enter  the  bladder  in  front  of  the  vagina  one 
and  one-half  inches  below  the  level  of  the  cervix.  Behind  : 
The  rectum,  from  which  it  is  separated  ;  above,  by  the 
rectovesical  fold  of  peritoneum  which  descends  between  the 
uterus  and  upper  inch  of  the  vagina  in  front  and  the  rectum 


THE  PERINEUM,  FEMALE.  431 

behind,  forming  the  pouch  of  Douglas  ;  below,  the  vagina 
is  separated  from  the  rectum  for  its  last  inch  by  the  fibrous 
structures  which,  taken  together,  form  the  "  perineal  body  ;  " 
in  the  middle  portion  the  vagina  lies  in  contact  with  the 
rectum.  At  the  sides  :  Above,  the  v'agina  is  crossed  by  the 
ureters  from  above  downward  and  forward  ;  below,  it  is 
■embraced  by  the  levatores  ani  muscles. 

The  mucous  membrane  (probably  modified  integument)  is 
thrown  into  longitudinal  ridges  upon  the  anterior  and  poste- 
rior walls  of  the  vagina.  These  ridges  are  called  the  columncB 
rugariivi.      They  extend  upward  from  the  vaginal  orifice. 

The  veins  form  a  plexus  about  the  vagina  and  commu- 
nicate with  the  hemorrhoidal  and  vesical  plexuses. 

The  arteries  are  from  the  anterior  division  of  the  internal 
iliac,  viz.  :  vaginal,  internal  pudic,  vesical,  and  uterine. 

The  nerves  are  from  the  internal  pudic,  the  fourth  sacral, 
and  the  hypogastric  sympathetic  plexus. 

The  Perineal  Body.      Fig.  85. 

This  is  the  mass  of  elastic,  fibrous,  and  connective  tissue, 
with  the  adjacent  portions  of  muscles,  which  fills  in  the 
space  between  the  lower  end  of  the  vagina  and  \'aginal 
orifice  in  front  and  the  rectum  and  anus  behind.  It  is  tri- 
angular in  anteroposterior  section,  the  base  at  the  integu- 
ment, the  apex  at  the  junction  of  the  vaginal  and  rectal 
walls.     The  sides  of  the  triangle  measure  about  an  inch. 

The  Uterus.      See  Pelvic  Viscera. 

The  Female  Urethra.      Figs.  85,  86. 

Is  about  one  and  one-half  inches  long  and  one-fourth 
inch  in  diameter.  It  lies  along  the  anterior  wall  of  the 
vagina.  It  opens  into  the  bladder  three-fourths  of  an  inch 
behind  the  middle  of  the  pubic  symphysis,  and  externall)- 
in  the  middle  line  just  in  front  of  the  orifice  of  the  vagina. 


432  A  MANUAL   OF  ANA  TOMY. 

THE  ABDOMEN,  Exterior. 

Boundaries. 

The  cavity  of  the  abdomen  is  limited  above  by  the 
thorax  and  diaphragm,  below  by  the  pelvis  and  levator  ani, 
behind  by  the  bodies  and  intervertebral  substances  of  the 
lumbar  vertebrae  and  adjacent  muscles,  laterally  and  in 
front  by  the  abdominal  muscles  and  their  aponeuroses. 

Landmarks.     Figs.  87,  98. 

Above  and  in  the  middle  line  is  the  ensiform  appe^idix ; 
extending  outward  and  downward  from  it  are  the  cartilagin- 
ous portions  of  the  seventh,  eighth,  and  ninth  ribs,  forming 
a  continuous  line,  then  the  tips  of  the  tenth,  eleventh,  and 
twelfth  ribs.  The  tip  of  the  tenth  idb  is  to  be  noticed  es- 
pecially, as  it  is  the  point  at  which  the  upper  horizontal 
line  is  drawn  in  mapping  out  the  abdominal  regions.  It 
can  easily  be  distinguished  from  the  others,  as  it  is  the 
first  freely  movable  rib  met  with  in  passing  from  the  ensi- 
form outward. 

Below,  there  is  in  the  middle  line  the  junction  of  the  two 
pubic  bones,  or  the  symphysis  pubis.  At  an  inch  externally 
is  the  spine  of  the  same.  If  the  subject  is  very  fleshy  the 
spine  of  the  pubes  is  concealed  and  difficult  to  locate  in 
the  usual  way,  but  by  invaginating  the  scrotum  (or  labium 
majus)  on  the  finger  and  abducting  the  thigh  so  as  to  ren- 
der tense  the  tendon  of  the  adductor  longus  muscle,  then 
carrying  the  finger  up  along  the  tendon  of  this  muscle  to 
its  origin,  the  spine  will  be  found  immediately  above  it. 
The  finger  can  also  be  entered  into  the  external  abdominal 
ring,  as  it  is  situated  just  over  and  to  the  outside  of  the 
spine.     The  spine  is  important  in   differentiating  inguinal 


Fig.  87.  The  Abdominal  Regions.— i,  A  vertical  line  drawn  from  the  middle 
of  Poupart's  ligament.  2,  The  upper  transverse  line  drawn  at  the  level  of  the  tip  of 
the  tenth  rib.  3,  The  lower  transverse  line  drawn  at  the  level  of  the  anterior  superior 
iliac  spines,  a,  a,  Nipples,  b,  b.  Tip  of  tenth  ribs,  c,  Ensiform  appendix,  rf,  Um- 
bilicus, e,  e.  Anterior  superior  iliac  spines.  4,  Ria:ht  hypochondriac,  5,  Epigastric, 
6,  Left  hypochondriac,  7,  Right  lumbar,  8,  Umbilical,  9,  Left  lumbar,  10,  Right  in- 
guinal, II,  Hypogastric,  12,  Left  inguinal,  regions. 

28 


434  A  MANUAL  OF  ANATOMY. 

from  femoral  hernia,  the  former  being  to  the  inside  and  the 
latter  to  the  outside  of  it.  More  externally,  and  always 
located  with  ease,  is  the  anterior  superior  spine  of  the 
ilium.  The  crest  of  this  bone  terminates  in  this  point, 
below  which  is  a  notch.  In  making  measurements  from 
this  point,  the  thumb,  over  which  is  stretched  the  measur- 
ing tape,  should  be  carried  up  from  below  until  arrested 
in  the  notch  below  the  spine.  When  the  measurement 
is  so  made,  the  spine  is  truly  a  "  fixed  point,"  but  as 
usually  performed,  by  trying  to  hold  the  thumb  or  finger 
upon  the  spine,  it  is  not  a  fixed  point,  as  the  measuring 
finger  will  slide  all  around  the  place  over  an  area  of  an 
inch. 

The  dense  band  of  fibres  stretching  between  the  anterior 
spine  of  the  ihum  and  the  spine  of  the  pubes,  formed  by 
the  aponeurosis  of  the  external  oblique  muscle,  isPoupart's 
ligament.  It  is  a  very  important  landmark.  The  um- 
bilicus is  always  present,  always  distinct,  hence  always 
easily  located.  Its  position  in  the  middle  line  a  little 
below  the  midpoint  between  the  ensiform  and  symphysis 
is  very  constant,  the  variations  not  amounting  to  enough 
to  render  it  unreliable  as  a  most  important  reference 
point.  Directly  behind  it  is  the  body  of  the  third  lumbar 
vertebra. 

Just  below  the  ensiform  the  abdominal  wall  is  depressed 
forming  the  "  pit  of  the  stomach"  or  scrobiculus  cordis. 
A  furrow  passes  from  this  depression  to  a  little  below  the 
umbilicus,  marking  the  linea  alba.  Below  this  the  abdomi- 
nal wall  is  not  depressed. 

The  masses  of  the  recti  muscles  and  the  shallow 
grooves  outside  of  them  are  usually  seen.  The  grooves, 
when  present,  lie  over  the  linea  semilunares.  The  masses 
of  the  recti  may  be  cut  up  transversely  by  shallow  depres- 


THE  ABDOMEN,  EXTERIOR.  435 

sions  at  the  ensiform,  umbilicus,  and  midway  between  the 
two.  These  transverse  markings  correspond  to  the  tendin- 
ous intcrsiXtio)is  in  the  recti  muscles. 

Abdominal  Regions.     Figs.  87,  98. 

The  abdomen  is  arbitrarily  divided  into  regions  by  four 
lines,  two  horizontal  and  two  vertical.  The  horizontal 
lines  are  drawn,  one  connecting  the  anterior  superior  spines 
of  the  ilium,  the  other  between  the  tips  of  the  cartilages  of 
the  tenth  ribs.  The  vertical  lines  are  formed  by  erecting 
a  perpendicular  at  the  middle  of  Poupart's  ligament  on  each 
side. 

The  regions  thus  formed  are  named  as  follows,  from 
right  to  left.  The  first  tier  :  The  right  hypochondriac,  the 
epigastric,  the  left  hypochondriac.  The  second  tier  :  The 
right  lumbar,  the  umbilical,  and  the  left  lumbar.  The 
third  tier  :  The  right  inguinal,  the  hypogastric,  the  left 
inguinal. 

The  portions  of  the  viscera  that  lie  in  the  above  regions 
may  be  determined  approximately  by  consulting  Figs.  96 
to  106.  It  is  to  be  noted  that  these  relations  are  not  constant 
for  the  same  subject  at  different  times,  or  for  any  two 
subjects  at  the  same  time.     At  best  they  are  only  relative. 

The  surface  area  of  the  various  viscera  will  be  given  in 
connection  with  the  description  of  those  viscera. 


DISSECTION. 
Shave  or  cut  the  hair  from  the  pubes. 

Incisions. — (i)   From  the  ensiform  to  the  symphysis,  then  along  the  dor- 
sum of  the  penis. 

(2)  Transversely  around  the  thorax  at  the  level  of  the  ensiform. 

(3)  From  the  symphysis  outward,  following  the  direction  of  Poupart's  liga- 
ment and  the  crest  of  the  ilium. 

Remove  the  integument  only,  from  this  area. 


436  A  MANUAL   OF  AA^A  TOMY. 

Superficial  Fascia.     Fig.  '^'i. 

This  consists  of  two  layers,  the  external  or  the  subcuta- 
neous, the  internal,  deep,  or  fascia  of  Scarpa. 

(i)  The  external  layer  is  composed  of  connective  and 
adipose  tissue,  the  varying  quantities  of  the  latter  determin- 
ing the  thickness  of  the  subcutaneous  tissue.  Above  it  is 
continuous  with  the  superficial  fascia  of  the  thorax,  and 
below  with  that  of  the  thigh. 

In  this  layer  lie  the  subcutaneous  vessels  and  nerves. 

The  more  important  of  the  vessels  are  {a)  The  super- 
ficial {superior)  extejnial  pudic,  which  forms  with  the 
artery  of  the  other  side  an  anastomotic  arch  over  the 
pubes,  and  at  the  side  of  the  root  of  the  penis  gives  off 
the  superficial  dorsal  artery  to  that  organ,  {fi)  The  super- 
ficial epigastric.  This  passes  upward  toward  the  umbilicus, 
having  crossed  the  middle  of  Poupart's  ligament.  These 
arteries  are  branches  from  the  femoral ;  for  their  origin, 
see  Dissection  of  Thigh.  They  are  usually  divided  in 
operations  upon  the  inguinal  lymphatics  and  herniot- 
omies, (r)  Numerous  cutaneous  arterioles  from  the  inter- 
costals,  lumbars,  deep  epigastrics,  and  superficial  circumflex 
iliacs. 

The  veins  take  the  names  of,  and  accompany,  the 
arteries. 

The  cutaneous  nerves  are  unimportant,  and  need  not  de- 
tain the  student  for  their  dissection.  They  come  from  the 
lower  intercostals  and  the  first  lumbar  nerves. 

The  Lymphatics.      Fig.  88. 

The  only  lymphatic  glands  of  any  importance  are  those 
grouped  around  the  superficial  epigastric  artery,  over  and 
above  the  middle  of  Poupart's  ligament.  They  drain  the 
superficial   region   of  the   lower  zone  of  the  abdomen,  the 


Fig:.  88      Dissection  of  the  Abdomen.— i,  Ensiform  aonendix     2   rre«;t  of 

the  Dubes  with'  th^^^n  >  external  pud.c  artery  It  forms  an  anastomotic  arch  over 
brL'Th  of  X  above  r'rh^H^'-;-  ^'  7^u^  superficial  dorsal  arterv  of  the  penis.  A 
fasc"a  of  the  ahHompn  '  J  I  ^^fi°^  ?'^ '^^  P^'""-  Continuous  with  the  superficial 
smaUanddono'tthowplalnlyr^'''""'  'P'^"'^"""  "^'"-    "^^^  '"^"'"^'  «'^"^s  were 


438  A  MANUAL   OF  ANA  TO  MY. 

upper  part  of  the  thigh,  the  perineum,  the  scrotum,  the 
anterior  two-thirds  of  the  urethra  and  superficial  parts  of 
the  penis  (external  genitals  in  the  female). 

The  connection  of  the  inguinal  lymphatics  with  the 
genitals  of  the  male  and  female  explains  why  they  be- 
come enlarged  in  inflammatory  conditions  of  those  parts. 
Such  enlargement  following  venereal  disease  is  termed  a 
bubo. 

The  removal  of  the  inguinal  glands  is  a  simple  operation 
on  the  cadaver,  but  in  the  living,  if  they  are  matted  together 
by  inflammatory  exudations,  it  may  become  quite  an  under- 
taking. 

(2)  The  deep  layer  of  the  superficial  fascia.  Fascia 
of  Scarpa.  Fig.  90.  This  is  a  thin  layer  of  tissue  in  the 
upper  part  of  the  abdomen,  where  it  passes  into  the  deep 
fascia  of  the  thorax  ;  below  the  umbilicus  it  forms  a  dense 
plane  that  backs  the  external  layer,  and  is  separated  from 
the  muscle  beneath  by  a  little  areolar  tissue.  It  is 
attached  in  the  middle  line  along  the  linea  alba,  below 
to  the  external  part  of  the  crest  of  the  ilium,  the  deep 
fascia  of  the  thigh  close  to  Poupart's  ligament  until  the 
spermatic  cord  is  reached,  over  which  it  is  reflected, 
then  to  the  front  of,  the  pubes  and  symphysis.  Over 
the  cord  and  from  the  front  of  the  symphysis,  the  two 
layers  of  the  superficial  fascia  become  firmly  united,  lose 
the  adipose  tissue,  acquire  elastic  and  muscular  fibres,  and 
thus  altered  in  structure  pass  over  the  penis  and  into  the 
scrotum  as  the  dartos  sheath,  then  into  the  perineum  to 
become  continuous  with  the  superficial  perineal  or  Colles' 
fascia.  See  page  404.  The  band  of  fibres  from  the  lower 
part  of  the  linea  alba  and  the  front  of  the  symphysis  which 
passes  on  to  the  penis,  forms  the  suspensory  ligament  for 
that  organ.      The  extension  of  the  fascia  through  the  scro- 


Fig.  89.  Dissection  OF  THE  Abdomen. — i,  The  ensiform  appendix.  2,  Muscle 
portion  of  tlie  e.xternal  oblique.  3,  Anterior  superior  iliac  spine.  4,  Aponeurotic  por- 
tion of  the  external  oblique.  5,  Poupart's  ligament.  6,  Outer  pillar  of  the  external 
abdominal  ring  7,  The  external  abdominal  ring  closed  by  the  external  spermatic 
fascia.  8,  The  internal  pillar  of  the  external  ring.  9,  The  spermatic  cord.  10,  Origin 
of  external  oblique.  11,  Umbilicus.  12,  Internal  oblique.  13,  The  linea  alba.  14,  The 
linea  semilunaris.  15,  The  iliohypogastric  nerve.  16,  The  inguinal  canal.  17,  Con- 
joined tendon.     18,  The  suspensory  ligament  of  the  penis. 


440  A  MANUAL  OF  ANATOMY. 

turn  to  the  perineum,  and  the  gap  left  over  the  cord, 
explains  how  extravasated  urine  may  find  its  way  from  the 
perineum  into  the  scrotum,  and  even  to  the  lower  abdomi- 
nal region. 

The  Penis.      Figs.  88  to  93. 

Is  divided  into  the  root  or  base,  at  the  symphysis  ;  the 
glans  or  head  ;  the  neck,  just  back  of  the  glans ;  and  the 
body,  between  the  neck  and  root. 

The  penis  is  slung  from  the  symphysis  pubis  by  the 
suspensory  lig-ament,  formed  from  the  deep  layer  of 
the  superficial  fascia  (Scarpa's),  of  the  abdomen.  See 
above. 

The  integument  covering  the  glans  is  called  the  pre- 
puce or  the  foreskin.  The  angle  of  the  penis  is  the  bend 
which  the  flaccid  organ  makes  at  the  symphysis  pubis. 

The  Superficial  Vessels  and  Nerves  of  the  Penis. — 
The  arteries  are  derived  from  the  superficial  external  pudic, 
the  nerves  from  the  terminal  branch  of  the  iliohypogastric. 
The  veins  are  venae  comites  of  the  arteries. 

The  Sheaths  of  the  Penis  are  described  in  connection 
with  the  Corpus  Spongiosum  on  page  414. 


DISSECTION. 
Incise  the  superficial  fascia  transversely  at  the  level  of  the  umbilicus  and 
vertically  in  the  middle  line.  Reflect  the  several  portions,  leaving  the  lower 
segment  fastened  by  its  lov?er  attachments.  Notice,  («)  the  iliohypogastric 
nerve,  which  appears  through  the  aponeurosis  of  the  external  oblique  above 
the  spine  of  the  pubes  and  passes  to  the  dorsum  of  the  penis.  (Superficial 
dorsal  nerve  of  the  penis.)  (b)  The  gap  in  the  superficial  fascia  over  the  sper- 
matic cord,  (c)  The  formation  of  the  suspensory  ligament  of  the  penis.  In- 
cise the  dartos  sheath  along  the  dorsum  of  the  penis,  reflect  it  laterally.  It 
will  be  found  continuous  with  the  superficial  fascia  of  the  abdomen  and  dartos 
of  the  scrotum. 


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442  A  MANUAL  OF  ANA  TOMY. 

The  Deep  Vessels  and  Nerves  of  the  Penis. — The 
arteries  are  from  the  internal  pudic,  page  412.  Nerves 
from  the  internal  pudic  nerve,  page  414. 

The  Dorsal  Vein  of  the  Penis.  (Usually  single,  may 
be  double.) 

This  emerges  from  a  venous  plexus  which  surrounds  the 
glans  penis,  passes  backward  along  the  dorsum  of  the 
penis  between  the  two  dorsal  arteries,  receives  in  this  part 
of  its  course  large  branches  from  the  body  of  the  penis 
which  emerge  from  between  the  corpus  spongiosum  and 
the  corpora  cavernosa  and  wind  around  the  side  of  the 
penis  to  enter  the  dorsal  vein. 

Continuing  backward,  the  vein  penetrates  the  suspensory 
ligament  of  the  penis,  then  passes  through  the  opening  in 
the  triangular  ligaments  close  to  the  under  surface  of  the 
pubic  arch,  divides  into  two  branches  which  terminate  in 
the  prostatic  plexus. 

Before  passing  through  the  triangular  ligaments  the 
dorsal  vein  sends  communicating  branches  to  the  internal 
pudic  veins.  See  page  413.  Within  the  pelvis  it  com- 
municates with  the  obturator  vein. 


DISSECTION. 

Divide  the  elastic  sheath  of  the  penis  along  the  median  line,  separating  the 
corpora  cavernosa  from  each  other,  and  from  the  corpus  spongiosum.  Consult 
the  descriptions  of  these  structures  as  already  given  on  pages  414,  416. 

Leave  the  corpus  spongiosum  attached  by  the  membranous  urethra  to  the 
prostate  and  bladder,  keep  them  covered  with  a  damp  cloth  until  such  time  as 
the  bladder  has  been  dissected  and  the  urethra  can  be  opened  from  end  to  end. 

Incise  the  skin  of  the  scrotum  along  the  median  raphe,  and  reflect  it. 
Identify  the  dartos  and  its  connections  with  the  superficial  abdominal  fascia, 
then  reflect  it  like  the  integument.      Remove  the  testicle  from  the  scrotum. 

The  various  coverings  of  the  cord  and  testicle  (Fig. 
93)  are  those  that  are  derived  from  the  several  layers  of  the 


THE  ABDOMEN,  EXTERIOR.  443 

abdominal  wall.  How  these  coverings  are  secured  is  ex- 
plained later  ;  only  their  names  can  be  given  now.  First  is 
the  dartos,  as  already  described.  Second,  the  external  sper- 
matic fascia.  Third,  the  cremasteric  fascia.  Fourth,  the 
infundibuliform  fascia.  Fifth,  the  extraperitoneal  tissue. 
In  addition  to  these  the  testicle  has  a  partial  envelope  formed 
of  peritoneum,  called  the  tunica  vaginalis. 

Of  these  various  layers  only  the  first,  third,  and  last  can 
be  demonstrated  apart  from  their  sources.  For  the  first, 
see  page  406  ;  for  the  second,  page  460  ;  the  last,  the  tunica 
vaginalis,  is  a  covering  the  testicle  has  acquired  from  the 
peritoneum,  see  page  460.  It  consists  of  two  layers  ;  the 
visceral,  enveloping  the  testicle,  except  at  its  posterior 
part ;  and  the  parietal,  forming  the  walls  of  the  sac  contain- 
ing the  gland. 

DISSECTION. 

Open  the  tunica  vaginalis  and  recognize  the  following  parts  ;  The  testicle 
proper  and  the  epididymis. 

The  tunica  albuginea  (Fig.  93)  is  the  dense  white 
fibrous  covering  of  the  testicle.  At  the  posterior  margin  of 
the  testicle  there  is  an  extension  from  this  capsule  into  the 
body  of  the  gland  of  a  fibrous  septum  called  the  mediasti- 
num, from  which  radiate  secondary  septa  dividing  the  organ 
into  lobes. 

The  epididymis  lies  at  the  back  of  the  testicle  and  is 
divided  into  the  head  or  globus  major,  the  body,  and  the 
tail  or  globus  minor,  from  which  the  vas  deferens  extends. 
See  page  542. 

Obliquus  Externus  Abdominis.      Fig.  89. 

Origin. — From  the  outer  surface  and  lower  margin  of 
the  eight  lower  ribs,  by  muscular  slips  that  interdigitate, 
the  three  lower  ones  wdth  the  latissimus  dorsi,  the  rest  with 
the  serratus  magnus. 


444  A  MANUAL   OF  ANATOMY. 

Insertion. — By  muscular  fibres  into  the  anterior  half  of 
the  external  lip  of  the  iliac  crest.  By  its  aponeurosis,  which 
unites  in  the  middle  line  with  the  opposite  muscle  (as  well 
as  all  the  other  lateral  abdominal  muscles),  to  form  the 
linea  alba,  extending  from  the  ensiform  to  the  symphysis. 
By  a  dense  band  of  the  aponeurosis,  which  extends  from 
the  anterior  superior  spine  of  the  ilium  over  the  femoral 
vessels  to  the  spine,  iliopectineal  line,  crest  and  front  of  the 
pubes.  The  portion  of  this  band  attached  to  the  spine  of 
the  pubes  is  Poupart's  ligament,  the  reflection  to  the  ilio- 
pectineal line  is  G-imbernat's  ligament. 

The  Linea  Alba.     Fig.  89.      Diag.  29. 

This  is  the  fascial  junction  of  all  the  lateral  abdominal 
muscles  in  the  middle  line  from  the  ensiform  appendix  to 
the  symphysis  pubis. 

A  gap  is  left  between  the  fibres  of  the  external  oblique 
over  the  spine  of  the  pubes,  through  which  passes  the  sper- 
matic cord  in  the  male  and  the  round  ligament  in  the 
female.  This  is  the  external  abdominal  ring  or  opening. 
Figs.  89  to  93. 

The  outer  border  of  the  ring  is  formed  by  Poupart's  liga- 
ment, the  inner,  by  the  fibres  of  the  aponeurosis  passing  to 
the  front  of  the  pubes  ;  these  borders  are  called  columns. 
In  order  to  strengthen  this  weak  spot  in  the  abdominal 
wall  these  columns  are  bound  together  by  fibres  passing  at 
right  angles  to  them,  and  extending  outward  to  near  the 
anterior  superior  iliac  spine.  These  fibres  constitute  the 
intercolumnar  fascia.  From  the  lower  part  of  the  inter- 
columnar  fascia  and  the  margins  of  the  ring  a  thin  membrane 
descends  upon  the  cord ;  this  is  the  external  spermatic 
fascia.  It  is  these  structures  that  close  in  the  gap  between 
the  separated  fibres  of  the  external  oblique  and  effectually 


Fig.  92.  Dissection  of  Testicles.— i,  Iliohypogastric  nerve.  2,  Poupart's 
ligament.  3,  3,  Spermatic  cord.  4,  4,  Tunica  vaginalis  laid  open.  5,  Head,  6, 
Body,  7,  Tail  of  the  epididymis.  The  head  is  also  called  the  globus  major  and  the 
tail  the  globus  minor.  8,  Testicle  enclosed  within  the  tunica  albuginea.  9,  Inter- 
columnar  fascia.  10,  Outer  pillar  (Poupart's  ligament).  11,  Inner  pillar  of  the  ex- 
ternal abdominal  ring.  12,  The  external  abdominal  ring.  13,  Ilio-inguinal  nerve. 
14,  Cremasteric.branch  of  deep  epigastric  artery.  15,  Testicle  enclosed  within  the 
tunica  vaginalis. 


446  A  MANUAL   OF  ANATOMY. 

obliterate  any  ring.  In  health  and  normally  there  is  no 
"ring."  In  this  connection  I  wish  to  caution  the  student 
in  reference  to  the  usual  anatomical  descriptions  of  "  rings," 
and  "canals."  In  the  living  subject  there  are  no  abdom- 
inal rings  except  during  the  descent  of  the  testicle  in  foetal 
life  or  of  a  hernia  at  a  later  period.  While  in  the  subject  a 
ring  exists  only  if  the  above  conditions  appertain,  or  as  a 
result  of  the  dissector's  labors.  These  so-called  abdominal 
rings  are  then  only  places  where  openings  can  be  made,  or 
are  "  potential  "  rings.  The  usual  habit  of  giving  measure- 
ments to  these  potential  rings  is  to  be  deprecated,  as  nor- 
mally there  are  no  rings,  and  if  made  by  the  dissector  they 
may  have  any  dimensions,  according  to  his  fancy  or  precon- 
ceived ideas.  By  applying  measurements  to  openings  that 
are  normal  only  at  a  certain  time  in  the  individual's  life  an 
erroneous  opinion  is  formed  of  the  true  relations  of  the 
parts,  that  will  interfere,  not  only  with  a  correct  anatomical 
knowledge  of  the  subject,  but  also  with  surgical  work  upon 
such  regions. 

The  Triangular  Fascia.      Fig.  89. 

Just  above  the  symphysis  some  fibres  of  the  external 
oblique  pass  across  the  median  line  to  be  inserted  in  the 
opposite  ilicpectineal  line  and  pubic  crest,  forming  a  small 
triangular  ligament  or  fascia.  The  triangular  ligament  lies 
behind  the  internal  column  of  the  external  abdominal  ring, 
and  in  front  of  the  conjoined  tendon.  It  will  not  be  seen 
until  the  external  oblique  is  reflected.  In  the  male  the 
spermatic  cord  escapes  from  the  external  ring  and  passes 
into  the  scrotum  ;  in  the  female  the  round  ligament  appears, 
to  quickly  become  lost  in  the  tissues  in  front  of  the  pubes. 

Actions  of  the  External  Oblique  Muscle. — To  protect,  also 
to  compress  the  abdominal  viscera,  and  thus  aid  defaecation, 


THE  ABDOMEN,  EXTERIOR.  447 

micturition,  v^omiting,  parturition,  expiration.  If  one  acts 
it  rotates  the  thorax  to  the  same  side,  or  the  pelvis  to  the 
opposite  side,  and  flexes  the  spine  laterally.  Both  acting 
will  flex  the  thorax  upon  the  pelvis  or  the  reverse. 

Nerve  Supply.      Page  453. 

DISSECTION. 
At  the  level  of  the  anterior  superior  spine  of  the  ilium  make  a  small  trans- 
verse cut  through  the  aponeurosis  of  the  external  oblique,  until  the  muscle 
beneath  is  seen.  Insert  a  knife-handle  or  finger  in  this  opening,  and,  raising 
the  external  oblique,  divide  it  transversely  toward  the  medial  line,  until  the 
linea  semilunaris  is  reached.  Reflect  the  upper  part  of  the  muscle,  first  raising 
it  carefully  from  the  one  beneath,  and  dividing  its  aponeurosis  over  the  linea 
semilunaris  ;  cut  away  the  two  or  three  upper  costal  attachments  of  the  muscle 
and  turn  it  backward  as  far  as  it  will  go.  The  lower  portion  is  to  be  turned 
back  in  a  similar  manner,  dividing  the  aponeurosis  as  near  the  linea  alba  as 
convenient,  and  down  to  the  pubis.  This  leaves  a  triangular  flap  attached  by 
Poupart's  ligament,  and  showing  the  external  ring. 

Obliquus  Internus  Abdominis.      Fig.  89. 

Origin. — From  the  posterior  layer  of  the  lumbar  fascia, 
from  the  anterior  two-thirds  of  the  middle  lip  of  the  iliac 
crest,  and  from  the  outer  half  of  Poupart's  ligament. 

Insertion. — By  the  conjoined  tendon  into  the  iliopectineal 
line  and  crest  of  the  pubes,  by  its  aponeurosis  into  the 
whole  length  of  the  linea  alba  from  ensiform  to  symphysis, 
and  by  muscular  fibres  into  the  lower  borders  of  the  last 
three  or  four  ribs. 

The  conjoined  tendon  is  formed  by  the  union  of  the 
fibres  of  the  internal  oblique  and  transversalis  muscles,  in- 
ternal to  the  middle  of  Poupart's  ligament,  into  a  common 
tendon,  that  is  inserted  into  the  iliopectineal  line  and  crest 
of  the  pubes.  The  conjoined  tendon  lies  directly  back  of 
the  external  abdominal  ring,  and  strengthens  this  naturally 
weak  spot.      The  fibres  of  the  muscles  passing  into  the  con- 


448  A  MANUAL   OF  ANATOMY. 

joined  tendon  arch  over  the  spermatic  cord  (or  round  liga- 
ment). 

In  the  angle  between  the  external  and  internal  oblique 
muscles  is  seen  the  cord  (or  round  ligament)  resting  upon 
Pouparfs  ligament,  and  disappearing  under  the  arching 
fibres  above  mentioned.  The  space  occupied  by  the  cord  or 
round  Hgament  is  the  ing-uinal  canal.  (Fig.  91.)  The  same 
remarks  apply  to  this  canal  that  were  made  in  reference  to 
the  abdominal  rings — it  is  not  a  canal  except  when  made 
such  by  a  hernia  or  by  the  dissector.  It  is  a  "  potential " 
canal.  It  extends  from  the  internal  to  the  external  abdom- 
inal rings,  a  distance  of  one  and  one-half  inches.  The  floor 
is  formed  by  Poupart's  ligament,  upon  which  the  cord  is 
seen  to  rest.  In  front  is  the  aponeurosis  of  the  external 
oblique  ;  behind,  the  conjoined  tendon,  internal  oblique,  and 
fascia  of  the  transversalis  (will  be  seen  later).  Above,  at 
outer  part,  the  muscular  arch  of  the  two  internal  muscles. 

As  the  cord  is  examined,  it  will  be  found  covered  with 
detached  loops  of  muscular  fibres,  which  are  reflected  upon 
it  in  gradually  lengthened  festoons  as  low  as  the  testicle. 
These  muscular  loops  constitute  the  cremaster  muscle,  and 
with  the  connective  tissue  binding  the  loops  together  is 
known  as  the  cremasteric  fascia.  The  cremaster  mus- 
cle is  usually  described  as  detached  portions  of  the  internal 
oblique.  Some  fibres  no  doubt  come  from  this  source,  and 
some  from  the  foetal  structure  called  the  gubernaculum. 
See  page  460. 

The  cremaster  is  supplied  by  the  genitocrural  nerve. 
There  is  neither  cremaster  muscle  nor  fascia  in  the  female. 

The  ilio -inguinal  nerve  (Fig.  92)  can  be  traced  from 
where  it  passed  through  the  external  ring,  upward  and  out- 
ward until  it  disappears  through  the  internal  oblique  and 
transversalis.      It  lies  close  to  Poupart's  ligament. 


Fig-  93-  Dissection  of  the  Abdomen. — i,  The  rectus  muscle  with  three  ten- 
dinous intersections.  2,  Inner,  3,  Outer  portion  of  the  anterior  layer  of  the  sheath 
of  the  rectus.  4,  Internal  oblique  reflected  inward.  5,  Intercostal  nerves.  6,  Trans- 
versalis  muscle.  7,  Muscular  branches  of  the  deep  circumflex  iliac  artery.  8,  Ilio- 
hypogastric nerve.    9,  Poupart's  ligament.     10,  Pyramidalis  muscle. 


29 


450  A  MANUAL   OF  ANA  TOMY. 

The  iliohypogastric  nerve  (Fig.  89)  appears  through 
the  internal  oblique  muscle  just  above,  and  an  inch  internal 
to  the  iliac  spine,  and  takes  a  course  downward  and  forward 
upon  the  internal  oblique. 

The  linea  semilunaris  (Fig.  89)  will  be  seen  at  the  outer 
border  of  the  rectus  muscle.  It  is  formed  by  the  junction 
of  the  aponeuroses  of  the  internal  oblique  and  transversalis 
muscles.  The  aponeurosis  of  the  internal  oblique  divides  into 
two  layers  at  the  outer  border  of  the  rectus  muscle  for  its 
upper  three-fourths.  Half  of  the  aponeurosis  passes  behind 
the  rectus  with  the  whole  of  the  transversalis  for  this  dis- 
tance, and  half  in  front  with  the  whole  of  the  external  ob- 
lique for  the  same  extent.  In  the  lower  fourth  the  blended 
aponeuroses  of  all  three  muscles  pass  in  front  of  the  rectus. 

Its  sheath  behind  in  the  lower  fourth  is  then  only  com- 
posed of  the  Fascia  of  the  Transversalis,  see  page  454. 

The  semilunar  fold  of  Douglas  (Fig.  94)  is  the  free 
margin  of  the  posterior  sheath  of  the  rectus  muscle.  It  is 
about  midway  between  the  umbilicus  and  the  pubes  (and 
of  course  behind  the  rectus). 

The  aponeurosis  of  the  external  oblique  joins  the  inter- 
nal oblique  inside  of  the  linea  semilunaris. 

Actions  of  htternal  Oblique. — Same  as  for  External,  q.  v. 

Nerve  supply. — See  page  453. 

DISSECTION. 

Incise  the  internal  oblique  muscle  transversely  inward  from  the  anterior 
superior  iliac  spine  to  the  linea  semilunaris,  and  vertically  from  the  same  point 
to  the  lower  border  of  the  ribs,  then  along  their  margin  until  the  outer  edge 
of  the  rectus  is  reached.  Reflect  this  quadrilateral  flap  of  internal  oblique, 
being  careful  to  leave  the  nerves  and  arteries  resting  upon  the  transversalis. 

Do  not  attempt  to  separate  the  lower  triangular  portions  of  the  internal 
oblique  from  the  transversalis,  as  they  are  so  intimately  blended  together  that 
the  separation  cannot  be  done  properly. 

The  posterior  portion  of  the  internal  oblique  can  be  cut  away  from  the 
ribs  and  crest  of  the  ilium  and  left  hanging  by  the  lumbar  fascia. 


THE  ABDOMEX,  EXTERIOR.  451 

Transversalis  Abdominis.      Figs.  91,  94. 

Origin. — By  fleshy  slips  from  the  inner  surfaces  of  the 
six  lower  costal  cartilages,  interdigitating  with  the  origins 
of  the  diaphragm.  From  the  lumbar  fascia,  and  the  ante- 
rior three-fourths  of  the  inner  lip  of  the  crest  of  the  ilium, 
and  from  the  outer  third  of  Poupart's  ligament. 

Insertion. — By  the  conjoined  tendon  as  given.  See  page 
447.  Into  the  whole  length  of  the  linea  alba,  which  it 
helps  to  form. 

The  Lumbar  Fascia.      Fig.  ^6.      Diag.  29. 

Consists  of  three  layers.  The  anterior,  from  the  bases 
of  the  transverse  processes  of  the  lumbar  vertebrae.  The 
middle,  from  the  tips  of  the  same  processes.  The  pos- 
terior, by  the  broad  sheath  of  the  erector  spinse  muscle 
from  the  spinous  processes  and  the  supraspinous  ligaments 
of  the  lumbar  and  adjoining  dorsal  and  sacral  vertebrae. 
Between  the  first  and  second  layers  is  the  quadratus  lum- 
borum  ;  between  the  second  and  third,  the  erector  spinae. 
That  portion  of  the  anterior  layer  extending  from  the  first 
lumbar  vertebra  to  the  tip  of  the  last  rib  is  called  the 
ligamentum  arcuatum  externum. 

Lying  upon  the  tranversalis  muscle  are  the  nerves  which 
are  passing  forward  to  supply  the  abdominal  muscles. 
They  are  the  lower  six  intercostal  and  the  iliohypogastric 
and  ilio-inguinal  from  the  first  lumbar. 

Along  with  the  nerves  are  found  branches  from  the 
intercostal  and  lumbar  arteries.  The  deep  circumflex  iliac 
artery  gives  off  several  large  branches  which  pass  upward 
between  the  internal  oblique  and  the  transversalis  muscles. 
In  the  dissection  of  the  preceding  muscles  it  has  been 
noticed  that  the  fibres  of  the  three  layers  run  obliquely  or 
at  risfht   angles  to  each   other.     The   fibres   of  the   trans- 


452 


A  MANUAL   OF  ANATOMY. 


versalis  pass  horizontally,  of  the  internal  oblique  upward 
and  forward,  of  the  external  oblique  downward  and 
forward. 

This  arrangement  insures  protection  against  ventral  her- 


Diag.  29.  The  Arrangement  of  the  Abdominal  Muscles  and  Lumbar 
Fascia.  {Fro7n  Holden.) — i,  Iliopsoas  fascia.  2,  Anterior  layer  of  lumbar  fascia. 
3,  Middle  layer  of  lumbar  fascia.  4,  Posterior  layer  of  lumbar  fascia.  5,  Aponeurosis 
of  external  oblique.  6,  Aponeurosis  of  internal  oblique.  7,  Aponeurosis  of  trans- 
versalis.  8,  Anterior  portion  of  sheath  of  rectus.  9,  Posterior  portion  of  sheath 
of  rectus,  a,  Rectus  abdominis,  b,  Transversalis.  c,  Internal  oblique,  d,  Ex- 
ternal oblique,  e,  Psoas  magnus.  /,  Quadratus  lumborum.  g,  Erector  spiiise  mass. 
h,  Latissimus  dorsi. 


nia,  and  is  made  use  of  in  some  operations  upon  the 
abdominal  viscera  where  the  incision  has  to  be  carried 
through   the   fleshy  part  of  the  muscles,  as  for  removal 


THE  ABDOMEN,  EXTERIOR.  453 

of  the  appendix  vermiformis,  or  for  the  formation  of  an 
artificial  anus  in  either  iliac  fossa,  the  criss-cross  arrange- 
ment of  the  fibres  forming  a  reliable  sphincter  in  the  latter 
case. 

DISSECTION. 
Incise  the  sheath  of  the  rectus  muscle  from  the  ensiform  to  the  symphysis, 
three-fourths  of  an  inch  from  the  linea  alba.  Reflect  the  two  portions, 
being  careful  to  avoid  cutting  into  the  muscle  at  the  tendinous  intersections, 
which  are  attached  to  the  anterior  portion  of  the  sheath,  but  not  to  the 
posterior. 

The  Pyramidalis.      Fig.  91. 

This  small  triangular  muscle  is  found  lying  upon  the 
rectus  at  its  lower  part. 

Origin. — From  the  crest,  anterior  surface  of  body  and 
symphysis  of  the  pubes. 

I)iscrtion. — B}'  a  slender  tendon  into  the  linea  alba,  half- 
way between  the  umbilicus  and  symphysis. 

Action. — To  make  the  linea  alba  taut,  to  assist  the 
rectus. 

Rectus  Abdominis.     Fig.  91. 

Origi)i. — By  a  direct  tendon  from  the  crest  of  the  pubes, 
by  a  reflected  tendon  from  the  structures  in  front  of  the 
symphysis  across  the  middle  line. 

Insertion. — Into  the  front  of  the  cartilages  of  the  fifth, 
sixth  and  seventh  ribs,  and  outer  margin  of  the  ensiform. 

Action. — To  compress  the  viscera  and  aid  in  all  expul- 
sive efforts,  as  defaecation,  micturition,  vomiting,  expira- 
tion, parturition.  To  flex  the  spine  anteriorly,  bringing 
the  thorax  and  pelvis  nearer  together. 

Nerve  Supply  for  all  the  Abdominal  Muscles. — The  six 
lower  intercostal  nerves  and  the  iliohypogastric  and  ilio- 
inguinal branches  of  the  first  lumbar  nerve. 


454  A  MANUAL   OF  ANA  TOMY. 

DISSECTION. 

Raise  the  rectus  from  its  sheath,  beginning  at  its  inner  margin.  The 
deep  epigastric  artery  will  be  seen  entering  the  posterior  part  of  the  muscle 
from  below  and  the  superior  epigastric  from  above.  The  deep  artery  is  a 
branch  of  the  external  iliac,  and  the  latter,  of  the  internal  mammary.  They 
anastomose  in  the  substance  of  the  rectus  and  form  the  longest  arterial  anas- 
tomosis in  the  body 

Divide  the  deep  epigastric  as  it  enters  the  muscle,  cut  the  nerves  at  the 
outer  border  of  the  muscle,  and  the  muscle  itself  at  its  middle.  Reflect  the 
two  portions. 

The  posterior  part  of  the  sheath  of  the  rectus  can  now 
be  seen.  The  upper  three-fourths  is  formed  by  the  apo- 
neurosis of  the  transversalis  with  one-half  of  the  internal 
oblique,  and  ends  below  in  a  free  border,  called  the  semi- 
lunar fold  of  Douglas,  midway  between  the  umbilicus  and 
the  symphysis,  or  at  the  junction  of  the  upper  three-fourths 
with  the  lower  one-fourth  of  the  rectus.  The  lower  one- 
fourth  is  formed  by  the  transversalis  fascia. 

DISSECTION. 

Cut  through  the  transversalis  from  the  fold  of  Douglas  to  the  anterior 
superior  iliac  spine,  saving  the  iliohypogastric  and  inguinal  nerves.  This 
gives  below  a  triangular  flap  consisting  of  the  fibres  of  the  transversalis  and 
internal  oblique  attached  by  the  conjoined  tendon  and  Poupart's  ligament. 

The  posterior  part  of  the  rectus  sheath  is  to  be  divided  along  the  linea  alba 
to  the  ensiform,  then  the  transversalis  and  overlying  muscles  removed  entirely 
from  their  attachments  to  the  ribs,  ilium,  and  lumbar  fascia.  The  peritoneum 
must  not  be  perforated  in  this  separation.  To  succeed  in  this  will  take  some 
time  and  patience. 

In  reflecting  the  lower  triangular  flap  do  not  take  up  the  fascia  transversalis, 
which  is  closely  united  to  the  muscle,  but  is  distinct  from  it. 

The  Fascia  Transversalis.      Fig.  94. 

This  is  a  layer  of  condensed  connective  tissue  interposed 
between  the  transversalis  muscle  and  the  extraperitoneal 
tissue.  It  is  thin  in  the  upper  region  of  the  abdomen 
where  it  becomes  continuous  with  the  fascia  covering  the 


Fig.  94.  Dissection  of  the  Abdomen. — i,  Superior  epigastric  artery.  2,  Rec- 
tus abdominis,  reflected.  3,  Posterior  portion  of  sheatli  of  the  rectus  abdominis.  4, 
Semilunar  fold  of  Douglas.  5,  Muscular  branches  of  deep  circumflex  iliac  artery  rest- 
ing upon  the  transversalis  muscle.  6.  Iliohypogastric  nerve.  7,  Ilio-inguinal  nerve. 
8,  Deep  epigastric  artery  covered  by  transversalis  fascia.  9,  Site  of  the  internal 
abdominal  ring.  10,  Poupart's  ligament.  11,  Deep  circumflex  iliac  artery,  having  a 
low  origin  below  Poupart's  ligament.  12,  Anterior  crural  nerve.  Lines  8  to  12  cross 
the  iliacus  muscle.  13,  Tensor  vaginae  femoris.  14,  Sartorius.  15,  Rectus  femoris. 
16,  Femoral  artery  lying  in  Scarpa's  space  or  triangle.  Notice  its  boundaries, 
floor,  and  contents.  17,  17,  Peritoneum.  The  parietal  layer.  18,  Inner  margin  of 
Douglas's  fold.  19,  Obliterated  hypogastric  arteries.  20,  Urachus.  21,  Spermatic 
cord.  22,  The  opening  (infundibular)  of  the  internal  abdominal  ring  in  the  trans- 
versalis fascia.  23,  Deep  epigastric  artery  and  relation  to  internal  abdominal  ring. 
24,  Transversalis  muscle,  reflected.  25,  Transversalis  fascia.  26,  Saphenous  opening. 
27,  Fascia  lata.  28,  Long  saphenous  vein.  29,  Pyriformis  muscle.  30,  Femoral  vein. 
31.  Adductor  longus  muscle. 


456  A  MANUAL  OF  ANA  TOMY. 

diaphragm,  but  becomes  thicker  as  the  inguinal  region  is 
approached,  and  when  Poupart's  ligament  is  reached  is  a 
membrane  of  considerable  density. 

Attachments. — Below,  to  the  crest  of  the  ilium,  to  the 
whole  of  Poupart's  ligament  (excepting  over  the  femoral 
vessels,  where  it  passes  under  Poupart's  ligament  to  form 
the  anterior  sheath  of  the  same),  to  the  outer  part  of  Gim- 
bernat's  ligament,  to  the  iliopectineal  line  and  inner  surface 
of  the  pubes  and  symphysis.  In  the  middle  line  it  is  con- 
tinuous from  side  to  side.  Laterally,  it  passes  into  the 
loose  tissue  in  those  parts.  Above,  it  becomes  continuous 
with  the  fascia  lining  the  diaphragm.  The  portion  of  the 
fascia  beneath  Poupart's  ligament  and  arching  over  the 
femoral  vessels  is  called  the  crural  arch. 

The  internal  abdominal  ring'  (Fig.  94)  is  a  potential 
opening  through  the  fascia  transversaUs,  formed  by  the  pas- 
sage through  it  of  the  spermatic  cord  in  the  male  and  the 
round  ligament  in  the  female.  It  is  situated  just  above  the 
middle  of  Poupart's  ligament.  From  the  margins  of  the 
internal  ring  there  is  a  thin  layer  of  membrane  projected 
upon  the  cord  (or  round  ligament)  ;  this  is  the  infundibuli- 
form  process  of  the  fascia  transversalis.  For  its  forma- 
tion, see  page  460. 

DISSECTION. 
Incise  the  transversalis  fascia  transversely  at  the  level  of  the  umbilicus  and 
along  the  middle  line,  providing  it  has  been  demonstrated  as  a  continuous 
layer ;  reflect  its  lower  portion,  which  is  thicker  than  the  upper  and  lies  in 
front  of  the  deep  epigastric  artery,  and  turn  this  portion  downward.  Trace 
the  deep  epigastric  artery  to  its  source,  raising  the  peritoneum  and  contents 
from  the  iliac  fossa.     Examine  the  relations  about  the  internal  ring. 

The  remaining  portion  of  the  deep  epigastric  artery  has 
been  exposed  by  this  dissection.  It  is  seen  to  arise  from 
the  front  of  the  external  iliac  close  to  Poupart's  Hgament, 


THE  ABDOMEN,  EXTERIOR.  457 

having  the  cord  or  round  ligament  curving  around  its 
outer  side,  and  passing  upward  and  inward  to  enter  the 
sheath  of  the  rectus  muscle,  over  the  semilunar  fold  of 
Douglas,  to  finalK^  inosculate  with  the  superior  epigastric 
in  the  substance  of  the  muscle. 

The  position  of  the  artery  is  between  the  two  abdominal 
rings,  or  to  the  inner  side  of  the  internal,  and  to  the  outer 
side  of  the  external  ring.  It  takes  part  in  the  formation  of 
Hesselbach's  triangle,  constituting  its  outer  side,  the  other 
boundaries  being  the  outer  margin  of  the  rectus  to  the 
inside  and  Poupart's  ligament  for  the  base.  Through  this 
triangle  the  direct  inguinal  hernia  must  pass. 

TJie  Formation  of  the  Abdomi)ial  Rings,  Coverings  of  the 
Testiele  and  Cord. — In  order  to  make  the  subject  clear  we 
must  turn  to  the  development  of  the  parts. 

Take  the  time  in  the  development  of  the  foetus  when  the 
testicle  is  at  the  back  part  of  the  abdomen,  below  the  kidney 
and  behind  the  peritoneum,  which  encloses  its  front  and 
sides,  forming  the  niesorcJiiiun.  The  testicle  has  the  giiber- 
itacidmn,  a  fibromiiscular  cord  passing  from  its  lower  border 
through  the  abdomen  to  be  attached  in  three  main  divisions, 
a  middle  band  passing  to  the  bottom  of  the  scrotum,  an 
anterior  one  to  the  structures  in  front  of  the  pubes,  a 
posterior  one  to  the  tissues  over  the  ischiatic  region. 

The  testicle  descends  to  reach  the  inner  surface  of  the 
abdominal  wall  and  the  gubernaculum  shortens  ;  whether 
the  testicle  descends  because  of  the  contraction  of  the 
gubernaculum,  or  its  shortening  is  only  an  incident  in  the 
descent  of  the  testicle,  are  disputed  points  with  no  wa}-  of 
solution.  The  testicle  is  preceded  in  its  descent  b\'  a  pro- 
cess of  the  peritoneum  which  is  drawn  downward  as  it  were 
by  the  gubernaculum.  It  also  takes  with  it  the  peritoneum 
by  which  it  is  nearly  enclosed.      Arriving  against  the  inner 


458 


A  MANUAL  OF  ANA  TOMY. 


surface  of  the  abdominal  wall  the  testicle  makes  no  hole, 
ring,  or  opening  through  its  layers  in  the  sense  of  a  division 
or  separation  of  fibres,  not  this,  but  it  bulges  in  front  of  it- 
self  first  the    transversalis    fascia,    then   the    transversalis 


Diag.  30.  Diagrammatic  Representation  of  the  Descent  of  the  Testicle 
AND  Formation  of  Abdominal  Rings  and  Coverings  for  the  Testicle  and 
Cord.  {I.S.H.) — i,  The  attachment  of  the  gubernaculum  to  the  peritoneum  above  the 
testicle.  2,  Its  attachment  to  the  testicle.  3,  Its  attachment  to  the  peritoneum  below 
the  testicle.  4,  Passage  of  gubernaculum  through  the  abdominal  wall.  5,  Anterior 
band  attached  over  pubic  region.  6,  Posterior  band  attached  over  ischiatic  region. 
7,  Middle  band  attached  to  base  of  scrotum. 


muscle,  and  internal  oblique,  and  finally  the  external  oblique  ; 
stretching  and  thinning  these  several  layers  in  front  of 
itself  it  carries  them  all  into  the  scrotum  to  form  the  cover- 
ings for  itself,  the   cord  and   for  any  hernia  following  this 


THE  ABDOMEN,  EXTERIOR. 


459 


course.  The  testicle  may  be  arrested  in  its  course  and 
never  leave  the  abdominal  cavity,  it  may  remain  in  the  in- 
guinal canal,  or  it  may  be  directed  to  the  front  of  the  pubes 
or  into  the  perineum  by  the  slips  of  gubernaculum  outside 
of  the  scrotum.     After  the  passage  of  the  testicle  these 


Diag.  31.  (/.  S.  H.)  See  Diag.  30. — i,  Vaginal  process  of  peritoneum.  2,  Infun- 
dibuliform  fascia.  3,  External  spermatic  fascia.  4,  Cremasteric  fascia.  5,  Tunica 
vaginalis.    6,  Remains  of  middle  band  of  gubernaculum. 


several  layers  of  the  abdominal  wall  contract  upon  the  cord 
where  it  passes  through  them,  and  the  funnel-shaped  proces- 
ses derived  from  them  become  so  thinned  that  in  the  adult 
they  cannot  be  demonstrated  except  close  to  their  points  of 
origin  (at  the  rings).  In  this  connection  consult  a  surgery 
for  the  various  forms  of  inguinal  hernia. 


460  A  MANUAL   OF  ANATOMY. 

The  covering  derived  from  the  transversalis  fascia  receives 
the  name  of  the  ijitejnial  spermatic  or  infundibuliform  fascia  ; 
that  from  the  internal  oblique  muscle,  partially  composed 
of  separate  muscle  loops  and  supporting  connective  tissue, 
forms  the  ere  master  muscle  {and  fascia^ ;  that  from  the  ex- 
ternal oblique  constitutes  the  external  spermatie  fascia.  By 
the  passage  of  the  testicle  into  the  scrotum  the  internal  and 
external  portions  of  the  gubernaculum  become  inverted, 
while  the  middle  remains  as  a  band  joining  the  gland  to  the 
bottom  of  the  scrotum.  The  inverted  portions  of  the  guber- 
naculum help  to  form  the  cremasteric  muscle  in  part.  The 
internal  and  external  bands  of  the  gubernaculum  sometimes 
draw  the  testicle  to  the  region  of  their  attachment ;  this  ex- 
plains the  abnormal  position  of  this  organ  in  front  of  the 
pubes  or  in  the  region  of  the  ischium  or  perineum.  If  the 
natural  process  is  arrested  the  testicle  may  never  leave  the 
interior  of  the  abdomen  or  it  may  be  left  in  any  part  of  its 
course  through  the  abdominal  wall  (at  any  point  in  the 
inguinal  canal). 

The  places  where  the  testicle  enters  and  leaves  the  ab- 
dominal wall  are  called  rings,  and  its  course  between  these 
points  the  inguinal  canal. 

As  the  testicle  descends  it  takes  with  it  a  tubular  process 
of  peritoneum  called  \he.fujiicular  process.  Naturally,  this 
tube  becomes  closed  at  the  internal  ring  and  close  to  the 
testicle,  and  the  intervening  portion  entirely  obliterated. 
The  portion  attached  to  the  testicle  forms  its  twtica  vaginalis. 

If  the  process  is  arrested  any  of  these  conditions  may 
prevail :  If  the  tube  remains  open  above,  fluid  may  pass  into 
it,  forming  a  congenital  hydrocele,  or  the  intestine  may  be- 
come prolapsed  into  the  tube,  giving  rise  to  a  congenital 
hernia.  If  it  becomes  closed  at  its  extremities  but  open 
between,  a  hernia  may  still   descend  behind  the  funicular 


THE  ABDOMEN,  EXTERIOR.  461 

process,  forming  the  infantile  variety  of  rupture  ;  in  this  case 
three  layers  of  peritoneum  intervene  between  the  bowel  and 
skin  ;  or  fluid  may  distend  the  tube,  producing  an  encysted 
hydrocele  of  the  cord. 

Even  if  nature's  processes  are  completed  a  hernia  may 
develop,  pass  out  through  the  internal  ring,  inguinal  canal, 
and  external  ring.  This  is  the  indirect  form  of  inguinal 
hernia.  If  the  hernial  protrusion  leaves  through  Hessel- 
bach's  triangle  (see  page  457)  and  appears  at  the  external 
ring,  it  becomes  the  direct  form  of  inguinal  hernia. 

TJic  coverings  of  the  indirect  inguitia/  hernia  are  these  : 
The  peritoneum,  extraperitoneal  tissue,  the  infundibuliform 
fascia,  the  cremasteric  fascia,  the  external  spermatic  fascia, 
the  superficial  and  deep  layers  of  the  superficial  fascia,  and 
the  integument. 

The  direct  inguinal  hernia  takes  a  course  through  Hessel- 
bach's  triangle  and  directly  out  through  the  external  ring. 
Its  coverings  are  the  peritoneum,  extraperitoneal  tissue, 
fascia  transversalis,  conjoined  tendon,  external  spermatic 
fascia,  two  layers  of  the  superficial  fascia  and  the  skin. 


DISSECTION. 

Raise  the  peritoneum  from  the  iliac  fossae,  exposing  the  iliac  vessels.  This 
shows  how  they  may  be  reached  and  ligated  without  opening  the  peritoneum. 

Clean  the  extraperitoneal  tissue  from  the  surface  of  the  peritoneum  ;  it  will 
be  found  thicker  in  the  lower  than  the  upper  part. 

Find  three  fibrous  cords  passing  from  the  umbilicus  downward  to  the  region 
of  the  bladder.  The  two  outside  ones  are  the  obliterated  hypogastric  arteries, 
the  middle  one  the  urachus.  The  arteries  return  the  blood  in  the  foetus  to  the 
placenta,  the  urachus  connects  the  bladder  with  the  allantois.  By  inflating 
the  bladder  these  cords  can  be  easier  dissected  out,  at  the  same  time  it  will  be 
seen  that  the  peritoneum  does  not  cover  the  anterior  wall  of  the  bladder  for  a 
distance  of  nearly  two  inches  above  the  pubes.  This  area  of  bladder  un- 
covered by  peritoneum  and  separated  from  the  inside  of  the  abdominal  wall 
by  extraperitoneal  tissue  is  the  space  of  Retzius.  Through  this  space  supra- 
pubic cystotomy  is  performed. 


462  A  MANUAL  OF  ANATOMY. 

THE  ABDOMEN,  Interior. 

The  Peritoneum.     Fig.  94. 

The  peritoneum  may  be  called  a  closed  sac  (in  the  fe- 
male it  is  not  strictly  such,  as  the  Fallopian  tubes  open  into 
it)  lining  the  abdominal  cavity.  Imagine  the  abdominal 
cavity  empty,  line  this  throughout  with  a  thin  membrane. 
From  the  back  push  in  the  alimentary  canal  and  the  organs 
connected  with  it,  from  below  the  urinary  viscera.  The 
thin  membrane  is  pushed  forward  by  the  various  organs 
which  receive  a  covering  from  the  membrane,  either  com- 
plete or  partial  according  to  the  extent  that  they  extend 
into  the  general  cavity.  This  membrane  is  the  peritoneum, 
the  layer  lining  the  abdominal  walls  is  the  parietal,  that 
covering  the  abdominal  organs  is  the  visceral. 

Leaving  the  adult  peritoneum  for  the  time,  it  will  be  ne- 
cessary to  follow  the  development  of  this  membrane  as 
well  as  that  of  the  abdominal  viscera  in  order  to  gain  a 
correct  idea  of  the  relations  as  they  are  found  in  the  adult. 
The  primitive  alimentary  canal  is  simply  a  straight  tube  ex- 
tending along  near  the  posterior  part  of  the  embryo  and 
held  to  this  position  by  a  fold  of  peritoneum.  This  fold 
of  peritoneum  forms  only  an  incomplete,  vertical  septum 
through  the  greater  portion  of  the  abdominal  cavity  (Diag. 
32,  Nos.  3,  4,  5),  but  in  the  upper  portion  this  fold  extends 
clear  forward  to  the  anterior  abdominal  wall  (Diag,  32,  No. 
7).  This  portion  of  the  septum  is  also  joined  to  the  under 
surface  of  the  diaphragm. 

The  alimentary  canal  soon  becomes  differentiated  by 
growth  into  stomach,  duodenum,  small  intestine,  and  large 
intestine. 

The  peritoneum  receives  different  names  according  to  the 


THE  ABDOMEX,  INTERIOR. 


463 


part  of  the  alimentan'  canal  to  which  it  is  attached.  That 
to  the  stomach  is  the  mesogaster,  to  the  duodenum  is 
mesoduodcnum.  to  the  small  intestine  is  mesentery,  to  the 


Diag.    32.       To   ILLUSTR.A.TE    THE    DEVELOPMENT     OF    THE  ALIMENTARY  CaNAL 

AND  Peritoneum.  The  development  is  traced  within  the  outlines  of  an  adult 
abdominal  cavity  in  order  to  make  the  subject  clearer.  (/.  5.  H.)—a,  Stomach. 
b.  Duodenum,  c.  Small  intestine,  d,  Large  intestine,  e.  Liver.  /,  Spleen,  g, 
Pancreas.  Ii.  Vitello-intestinal  duct,  i,  Mesogaster.  2,  Mesoduodenum.  ,-?,  Mesen- 
tery. 4,  Mesocolon.  5,  Mesorectum.  6,  Gastrohepatic  omentum.  7,  Suspensory 
ligament   of  liver. 

large  intestine  mesocolon,  then  mesosigmoid,  and  meso- 
rectum. 

There  are  arteries  developing  during  this  stage.      Along 
the  back  of  the  foetus  is  the  aorta,  lying  between  the  two 


464 


A  MANUAL   OF  ANATOMY. 


folds  of  the  peritoneum  that  attaches  the  ahmentary  canal 
to  the  back  of  the  foetus.  From  the  aorta  branches  pass 
to  the  various  parts  of  the  intestinal  tube  :  To  the  stomach 

passes  the  gastric ;  to  the 
small  and  large  intestine  the 
superior  mesenteric ;  and  to 
the  large  intestine  the  inferior 
mesenteric.  All  these  arteries 
run  to  their  distribution  be- 
tween the  folds  of  the  peri- 
toneum which  encloses  the 
alimentary  canal. 

The  growth  of  the  bowel 
is  mostly  below  the  stomach 
and  duodenum,  and  takes 
place  faster  than  the  growth 
of  the  corresponding  part  of 
the  peritoneum,  consequently 
the  small  intestine  is  thrown 
into  numerous  folds. 

One  of  these  folds  is  in  the 
duodenum  and  another  in  the 
large  intestine  (Diag.  33,  b). 
As  development  proceeds  the 
bend  in  the  large  intestine  is 
broug-ht   nearer   to   the   duo- 


Diag.   33.      A    Second    Stage  in 
THE  Process   of  Development.     (I. 
S.   H.) — Increase    in    size    of  stomach, 
length  of  small  intestine,  and  size  and      dcnal  CUrVC  and  the  mCSCntcry 
length  of  large  intestine.     Decrease   in      ^^^,,\^^^       ^       ^,'c-f;,-,/-f      "  '^  C  k 


size  of  vitello-intestinal  duct. 


acquires     a    distinct     n  e 

(Diag.  34.) 
There   now   occurs   a    most   interesting   change.       This 
change  is  the  rotation  of  the  intestinal  tract  below  the  duo- 
denum on  the   superior  mesenteric   artery  as   an   axis,  the 
large  intestine,  or  the  colic  part  of  it,  passing  from  the  left 


THE  ABDOMEN,  INTERIOR. 


465 


up  over  the  duodenum  to  the  right  to  a  position  at  the  right 
side  of  the  abdominal  ca\ity,  while  the  small  intestine  passes 
to  the  left  and  lies  within  the  arch  formed  by  the  large  in- 


Diag.  34.  A  Third  Stage  in  the  Process  of  Development.  (/.  .S".  H.)  The 
large  intestine  having  passed  upward  and  crossed  from  left  to  right  in  front  of  the 
duodenum. — a,  Stomach,  b.  Duodenum,  c,  Small  intestine,  d.  Large  intestine 
now  differentiated  into  several  portions — as  i.  Vermiform  appendix.  7,  Caecum. 
k,  Transverse  colon  (ascending  colon  not  yet  developed).  /,  Descending  colon,  m. 
Omega  loop,  n,  Rectum,  e,  Liver.  /,  Spleen,  g.  Pancreas,  i,  Mesogaster.  2, 
Mesentery,      3,   Mesocolon. 


testine.     (Diags.  34  and  35.)     This  rotation  forms   a  twist 
in  the  mesenteric  stalk  and  a  fossa  that  remains  in  the  adult 
as  the  duodenojejunal  fossa. 
30 


466 


A  MANUAL  OF  ANA  TOMY. 


At  the  beginning  there  is  no  separation  between  the  ab- 
dominal and  thoracic  cavities  ;  such  a  division  is  formed 
later  by  the  development  of  the  diaphragm.  The  meso- 
gaster  does  not  stop  with  the  stomach,  but  passes  forward 


Diag.  35.  The  Final  Stage  in  the  Process  of  Development.  (/.  5.  H.) 
The  alimentary  canal  in  its  adult  position.— a,  Stomach,  b,  Duodenum,  c,  Small 
intestine,  d,  Vermiform  appendix,  e.  Caecum,  f.  Ascending  colon,  g,  Hepatic 
flexure,  h.  Transverse  colon,  z,  Splenic  flexure.  7,  Descending  colon,  k.  Omega 
loop.    /,  Rectum. 


to  the  anterior  abdominal  wall  and  diaphragm,  on  to  which 
it  is  reflected.  Within  the  two  layers  of  the  anterior  meso- 
gaster  (in  front  of  the   stomach),  and  springing  from   the 


THE  ABDOMEN,  INTERIOR.  467 

duodenum,  to  which  it  is  connected  by  a  duct,  is  a  mass 
of  budding  cells  that  subsequently  forms  the  liver.  The 
fcetal  liver,  then,  is  in  front  of  the  stomach,  between  the 
layers  of  the  anterior  mesogaster  (future  hepatic  ligaments 
and  gastrohepatic  omentum),  by  which  it  is  connected  to 
the  diaphragm  the  stomach,  and  duodenum.  Into  the  last 
opens  the  duct  of  the  liver.  Behind  the  stomach  another 
mass  of  cells  springs  up  from  whose  growth  the  spleen  is 
formed  ;  this  also  develops  between  the  two  layers  of  the 
mesogaster.  In  the  same  way  the  pancreas  springs  from  a 
mass  of  cells  in  the  mesoduodenum  (posterior  to  the  gut). 
(Diags.  32,  33,  34,  c.f.g?) 

Coincident  with  the  rotation  of  the  small  and  first  parts 
of  the  large  intestine,  the  stomach,  first  part  of  duodenum, 
and  liver  turn  over  toward  the  right  side  of  the  abdominal 
cavity  (Diag.  35),  while  the  spleen  is  crowded  over  to  left 
side  of  the  abdomen. 

In  order  to  understand  these  new  relations  and  how  they 
come  to  be  formed,  we  must  consider  how  the  peritoneal 
attachments  can  be  shifted. 

There  is  more  surface  to  be  covered  than  there  is  peri- 
toneum to  cover  it.  Some  parts  must  be  only  partially 
covered  by  peritoneum  in  this  case  ;  this  is  what  really  oc- 
curs. In  the  beginning  there  is  enough  peritoneum  to 
cover  the  primitive  gut,  but  the  gut,  liver,  spleen,  etc., 
growing  faster  than  the  peritoneum,  some  of  them  become 
deprived  of  their  peritoneal  covering  in  part.  The  attach- 
ments of  the  peritoneum  to  the  abdominal  wall  are  also 
shifted  by  the  peritoneum  being  drawn  up  in  one  direction 
more  than  in  another,  until  the  base  of  the  original  attach- 
ment is  completely  altered.  For  instance,  the  colon  rotates 
to  the  right  side  of  the  abdomen,  the  right  layer  of  the 
mesocolon  is  taken  up  by  the  growth  of  the  other  abdomi- 


468  A  MANUAL   OF  ANA  TOMY. 

nal  organs  (chiefly  the  Hver),  until  the  colon  may  be  left 
covered  only  in  front  and  at  the  sides  (the  usual  condition), 
or,  less  peritoneum  being  drawn  off  from  the  colon,  there 
will  be  left  a  distinct  mesocolon  of  varying  length.  In  the 
same  manner  the  entire  attachment  of  the  gut  below  the 
stomach  is  moved  to  the  left. 

As  a  part  of  this  process  of  peritoneal  alterations  the 
Formation  of  the  Omeittuni  must  next  be  explained. 

It  is  formed  by  the  pouching  to  the  left  and  forward  of 
the  mesogaster  below  the  spleen  and  as  far  as  the  duo- 
denum. 

This  bag  will  be  composed  of  two  layers  of  the  peri- 
toneum originally  forming  the  mesogaster.  It  comes  to 
hang  down  over  the  intestines  covering  them  in.  In  a  ver- 
tical section  of  the  fcetus  from  before  backward,  the  dilated 
bag  of  mesogaster  (omentum)  is  seen  to  come  off  from 
the  lower  part  of  the  stomach,  and  after  making  the  down- 
ward loop,  to  return  to  the  back  of  the  abdomen,  where 
it  is  attached  :  the  transverse  mesocolon  and  the  mes- 
entery are  attached  separately  and  in  this  order  below  the 
posterior  omental  attachment.      (Diags.  36,  37.) 

As  growth  goes  on,  the  under  layer  of  omentum  is 
drawn  away  from  the  spine  and  then  from  the  upper  part 
of  the  colon,  while  the  inner  layer  comes  to  rest  upon  the 
colon  and  to  form  the  upper  layer  of  its  mesocolon.  (Diag. 
38.)  This  gives  the  typical  formation  seen  in  the  adult 
vertical  anteroposterior  sections.  If  the  process  is  inter- 
rupted, the  foetal  condition  prevails  and  the  omentum  is 
separate  from  and  above  the  transverse  mesocolon  at  their 
posterior  attachments.  (Diag.  37.)  This  failure  of  develop- 
ment is  a  predisposing  condition  to  volvulus  of  the 
bowel. 

The  omentum  passing  to  the  colon  and  becoming  attached 


THE  ABDOMEN,  INTERIOR. 


469 


to  it  in  the  above  manner  is  called  the  gastrocolic  or  the 
great  omentum,  to  distinguish  it  from  the  peritoneal  bands 


Diag.  36.  The  Development  of 
THE  Great  Omentum.  {Modified  from 
Minot.)  The  abdominal  viscera  are  sup- 
posed to  be  in  their  final  stage  of  develop- 
ment while  the  peritoneum  is  drawn  in 
its  foetal  state.— a,  Liver,  d,  Stomach. 
(T,  Transverse  colon,  d.  Small  intestine. 
T,  Gastrohepatic  omentum.  2,  Mesogaster 
from  the  stretching  of  which  the  great 
omentum  is  formed.  3,  Mesocolon.  4, 
Mesentery.  5,  Cavity  of  great  omentum. 
6,  General  peritoneal  cavity.  5,  and  6, 
communicate  at  right  of  gastrohepatic 
ometitum  (foramen  of  Winslow). 


Diag.  37.  A  Second  Stage  in 
the  Development  of  the  Great 
Omentum.  {Modified  from  Minot.') 
The  condition  here  represented,  viz.  of 
the  great  omentum  passing  for  a  sepa- 
rate attachment  to  the  back  of  the 
abdominal  cavity  above  the  transverse 
mesocolon  sometimes  is  found  to  pre- 
vail in  the  adult.  Letters  and  numbers 
as  in  Diag.  36. 


joining   the    stomach  to  other  abdominal  viscera,  as   the 


470  A  MANUAL  OF  ANA  TOMY. 

gastrohepatic  and  gastrosplenic  omenta  to  the  liver  and 
spleen,  respecti\ely. 

The  cavity  of  the  great  omentum  is  also  called  the  cavity 
of  the  lesser  peritoneum.  It  communicates  with  the  gen- 
eral peritoneal  cavity  by  means  of  the  opening  to  the  right 
and  behind  the  gastrohepatic  omentum,  which  in  the  foetus 
is  a  very  wide  opening,  but  in  the  adult  the  primitive  rela- 
tions have  become  so  altered  that  this  opening  will  only 
admit  two  fingers,  and  receives  the  name  of  the  foramen 
of  Winslow. 

The  posterior  attachment  of  the  peritoneum  in  the 
foetus  is,  as  already  stated,  in  a  straight  line  ;  in  the  adult  it  is 
in  several  lines,  none  of  which  are  straight.  (Diag.  39.)  The 
course  in  the  adult  that  represents  the  primitive  peritoneal 
attachment  is  above,  beginning  with  the  falciform  ligament  of 
the  liver,  through  the  gastrophrenic  ligament  of  the  stomach, 
the  gastrosplenic  omentum  (all  that  is  left  of  the  original 
mesogaster),  then  to  the  attachment  of  the  descending  meso- 
colon, the  sigmoid  mesentery,  and  the  mesorectum,  the 
last  coming  back  to  the  middle  line  in  the  lower  part  of  its 
course,  all  the  rest  lying  to  the  left  of  the  middle  line. 
The  other  adult  attachments  are  acquired  in  the  manner 
already  explained.  They  are  for  the  small  intestines  and 
the  ascending  and  transverse  colon.  The  mesenteric  at- 
tachment starts  above  to  the  left  of  the  second  lumbar  ver- 
tebra and  passes  downward  to  the  right  iliac  fossa.  From 
the  last  point  the  mesentery  for  the  ascending  colon  extends 
upward  to  the  lower  border  of  the  thorax,  then  turns  to  the 
right,  forming  the  transverse  mesocolon.  At  the  upper  end 
of  the  ascending  colon  a  band  of  peritoneum  passes  off 
horizontally  to  be  attached  to  the  lateral  abdominal  wall 
between  the  crest  of  the  ilium  and  the  lower  border  of  the 
thorax.      Upon  this  shelf  the  right  extremity  of  the  liver 


THE  ABDOMEN,  INTERIOR. 


471 


rests,  hence  it  is  called  the  sustentaculum  hepatis.     Sim- 
ilarly, at  the  point  where  the  transverse  colon  bends  down- 
ward to  form  the  descending  colon,  a  peritoneal  process 
passes  outward  to  the  tenth  rib  ; 
this     band    is    the     costocolic 
ligament,     or,     as    the     spleen 
rests  upon  it,  the  sustentaculum 
splenis. 

To  return  to  the  fcetal  con- 
dition once  more,  from  the  front 
of  the  small  intestine  a  duct 
passes  off  to  the  yolk  sac  ;  this 
is  the  vitello-intestinal  duct. 
Usually  this  duct  becomes 
entirely  obliterated,  but  some- 
times it  may  persist  in  the  adult 
as  Meckel's  divcrticiihiui,  usually 
as  a  very  short,  blind  tube,  from 
one  to  three  feet  from  the 
caecum  ;  less  often  does  it  reach 
any  considerable  length,  but 
when  it  does  it  may  become  a 
menace  to  the  individual  from 
forming  adhesions  and  a  portion 
of  the  bowel  being  strangulated 
by  it. 

Peritoneal  reflections  as  seen 
when   the    abdomen    is    opened 

in  the  adult.  The  peritoneum  is  divided,  for  purposes 
of  description,  into  various  parts,  depending  upon  the  loca- 
tion. The  portion  of  the  membrane  lining  the  interior  of 
the  abdominal  cavity  is  called  the  parietal  layer,  that  cover- 
ing the  abdominal  organs,  the  visceral.     The  peritoneum 


Diag.  38.  The  Final  Stage  in 
THE  Development  of  the  Great 
Omentum.  Letters  and  numbers  as 
in  Diag.  36. 


472 


A  MANUAL  OF  ANA  TOMY. 


passing  between  various  parts  of  the  viscera,  or  viscera  and 
abdominal  wall,  is  further  classified  as  omentuni,  that  is,  peri- 
toneum attaching  the  stomach  to  adjacent  organs,  as  gastro- 
hepatic,  gastrocolic,  and  gastrosplenic  omenta  ;  mesentery, 


Diag.  39.  The  Parietal,  Peritoneal  Attachments  of  the  Abdominal 
Viscera.  {From  Cunninghayn,  in  J/on-is's  Anatomy.) — a,  Falciform  ligament  of 
liver,  b.  Left  lateral,  c,  Right  lateral  ligaments  of  liver,  d,  Inferior  vena  cava,  e. 
Gastrophrenic  ligament.  _/",  CEsophagus.  g,  Gastrosplenic  omentum,  h,  Splertic 
artery,  i,  Costocolic  ligament.  j,j,  Transverse  mesocolon,  k,  k,  Descending  colon. 
/,  Sigmoid  mesocolon,  m,  Mesorectum.  n,  Bladder,  o,  o,  Mesentery,  p,  p,  Ascend- 
ing colon,  g,  Caecum,  r,  Vermiform  appendix,  s,  Inferior  vena  cava,  t,  Duo- 
denum. M,  Duodenum,  z/.  Abdominal  aorta,  i,  Cavity  of  great  omentum.  2,  Fora- 
men of  Winslow. 

the  peritoneal  attachment  of  the  intestine  below  the  stomach 
to  the  posterior  abdominal  wall,  the  part  of  the  bowel  being 
indicated  by  a  combination  of  the  term  meso-  and  the  por- 
tion of  the  bowel,  as  mesoduodenum,  mesocolon,  sigmoid- 


THE  ABDOMEN,  INTERIOR.  473 

mesentery,  mesorectum  ;  and  lig-ament,  the  process  of  peri- 
toneum that  connects  and  supports  organs  not  parts  of  the 
alimentary  canal,  as  the  ligaments  of  the  liv^er,  uterus,  etc.  ; 
exceptions   are  the  gastrophrenic  and  costocolic  ligaments. 

The  hollows  formed  by  the  reflections  of  the  peritoneum 
are  called  fossae,  the  position  being  indicated  by  the  names 
of  the  parts  between  which  the  fossa  is  formed,  as  recto- 
vesical fossa. 

The  anterior  parietal  layer  of  peritoneum  has  been  ex- 
posed. It  is  seen  to  cover  the  abdominal  organs  and  reach 
from  the  pelvic  cavity  to  the  under  side  of  the  diaphragm. 
Attention  has  already  been  called  to  the  fact  that  the  peri- 
toneum can  be  raised  from  the  iliac  fossa;,  exposing  the 
vessels  there.  The  membrane  is  now  to  be  opened  by  an 
incision  from  the  ensiform  to  the  symphysis  at  the  left  of 
the  middle  line,  and  one  horizontally  across  just  below  the 
umbilicus. 

Reflect  the  four  segments.  Attached  to  the  right  upper 
one  are  two  ligaments  of  the  liver.      Save  these.     Diag.  40. 

To  follow  the  peritoneum,  the  membrane  is  seen  lining 
the  under  surface  of  the  diaphragm  to  the  posterior  portion  ; 
it  then  is  reflected  on  to  the  liver  and  the  oesophageal  end 
of  the  stomach,  forming  the  anterior  layer  of  the  coronary 
and  lateral  lig-aments  of  the  liver  and  the  gastrophrenic 
ligament  of  the  stomach  ;  then,  covering  the  upper  surface 
of  the  liver,  the  peritoneum  turns  over  its  anterior  border 
to  line  its  under  surface  as  far  backward  as  the  point  of 
entrance  of  the  hepatic  vessels  ;  at  this  place  the  membrane 
descends  to  the  lesser  curvature  of  the  stomach,  forming 
the  anterior  layer  of  the  gastrohepatic  omentum. 

The  peritoneum  covers  the  entire  anterior  surface  of  the 
stomach  and  first  portion  of  the  duodenum,  and  from  the 
greater  curvature  of  the  former  and  front  of  the   latter  this 


474  A  MANUAL  OF  ANA  TOMY. 

anterior  layer  (having  been  joined  by  the  peritoneum  cover- 
ing  the  posterior  wall    of  the    stomach,  vide  infra)    falls 


Diag.  40.  A  Diagrammatic  Median  Anteroposterior  Section  of  the 
Abdominal  Cavity,  to  Illustratp;  the  Reflections  of  the  Peritoneum.  {Mod- 
ified from  Quain.) — a.  Liver,  b,  Stomach,  c,  Transverse  colon,  d,  Small  intestine. 
e,  Spleen,  f,  Pancreas,  g.  Bladder,  h.  Uterus.  «,  Vagina.  7',  Rectum,  i,  Gastro- 
hepatic  omentum.  The  arrow  passes  around  its  right  (free)  margin  from  6,  the  general 
peritoneal  cavity,  into  5  the  cavity  of  the  great  omentum  through  the  foramen  of 
Winslow.  2,  Great  omentum.  3,  Transverse  mesocolon  within  which  is  the  superior 
mesenteric  artery.  4,  Mesentery.  5,  Cavity  of  great  omentum.  6,  General  peri- 
toneal cavity.    7,  Uterovesical  pouch.    8,  Pouch  of  Douglas. 


downward  in  a  broad  fold  over  the  small  and  large  intes- 
tines and  returns  behind  this   first  layer  to  be   attached  to 


Fig.  95.  Abdominal  Viscera  (Male).  [Subject  horizontal.] — i,  Left  lobe 
liver.  2,  Falciform  ligament  of  the  liver.  3,  Stomach.  4,  Umbilicus.  5,  5,  Great 
omentum  covering  intestines.  6,  Obliterated  hypogastric  arteries.  7,  Urachus.  8, 
Right  lobe  liver.  9,  Crest.  10,  Anterior  superior  spine  of  ilium.  11,  Deep  circumflex 
iliac  artery.  12,  Poupart's  ligament.  13,  E.xternal  iliac  artery.  14,  Deep  epigastric 
artery.  15,  Spermatic  cord.  Notice  the  relations  of  14  and  15.  16,  Pubic  branch  of 
14.  17,  Symphysis  pubis.  18,  Pubic  spine.  19,  Bladder  moderately  distended.  20, 
Site  of  femoral  ring.     21,  External  iliac  vein. 


476  A  MANUAL  OF  ANATOMY. 

the  transverse  colon.  This  is  the  great,  or  gastrocolic 
orQentum. 

Raise  the  great  omentum  and  with  it  the  transverse 
colon.  The  peritoneum  passing  from  this  part  of  the  colon 
to  the  posterior  abdominal  wall  is  the  lower  layer  of  the 
transverse  mesocolon. 

From  the  posterior  attachment  the  peritoneum  extends 
down  upon  the  small  intestines  ;  enclosing  them,  it  returns 
to  the  abdominal  wall,  these  two  surfaces  forming  the  right 
upper  and  left  lower  layers  of  the  mesentery.  It  will  be 
seen  that  the  mesentery  has  a  short  base  which  is  attached 
to  the  abdomen  in  an  oblique  line  extending  from  the  left 
of  the  second  lumbar  vertebra  downward  to  end  in  the 
right  iliac  fossa,  that  its  intestinal  end  equals  the  length  of 
the  small  intestine,  that  its  width  is  about  eight  inches. 

From  the  lower  end  of  the  mesentery  the  peritoneum  is 
seen  to  cover  the  beginning  of  the  large  intestine — the 
caecum — and  the  little  process — ^the  vermiform  appendix 
— that  extends  off  from  it.  The  appendix  has  a  narrow 
mesentery,  the  caecum  has  none  ;  both  are  free  in  the  peri- 
toneal cavity.  Upward  from  the  caecum  passes  the  as- 
cending colon,  which  is  found  covered  with  peritoneum  in 
front  and  at  the  sides,  that  at  the  right  being  continued  as 
the  lining  or  parietal  layer  of  the  abdomen,  that  to  the  left 
being  continued  into  the  right  surface  of  the  mesentery. 
Sometimes  the  colon  has  a  distinct  mesentery. 

The  bend  formed  by  the  junction  of  the  ascending  and 
transverse  colon  is  the  hepatic  flexure  ;  from  its  outer  bor- 
der an  extension  of  the  transverse  mesocolon  is  found 
which  is  attached  to  the  adjacent  abdominal  wall.  This  is 
the  sustentaculum  hepatis,  because  the  right  extremity 
of  the  liver  rests  upon  it. 

At  the  left  the  transverse  colon  takes   a   sudden  bend 


THE  ABDOMEN,  INTERIOR.  477 

downward  to  become  the  descending-  colon.  This  bend  is 
the  splenic  flexure.  At  this  point  the  transverse  mesocolon 
is  seen  to  be  continued  to  the  under  surface  of  the  tenth 
rib,  forming  the  costocolic  ligament  or  the  sustentacu- 
lum splenis,  as  it  supports  the  spleen. 

The  descending  colon  is  covered  like  the  ascending, 
front  and  sides,  the  peritoneum  at  the  right  passing  into 
the  left  lower  surface  of  the  mesentery,  to  the  left,  to  line 
the  lateral  abdominal  wall.  In  both  the  posterior  surface 
is  usually  bare  ;  this  allows  the  bowel  to  be  entered  from 
the  back  without  opening  into  the  general  peritoneal  cavity. 
The  large  loop  of  intestine  following  the  descending  colon 
is  the  omega  loop,  or  the  sigmoid  flexure.  It  has  a  dis- 
tinct mesentery  about  three  inches  long  and  the  same 
width.  This  allows  the  gut  to  hang  free  in  the  pelvic 
cavity.  When  the  hollow  of  the  sacrum  is  reached  the 
peritoneum  passes  around  to  cover  in  the  front  of  the  rec- 
tum, descending  to  a  point  about  an  inch  above  the  level 
of  the  tip  of  the  coccyx,  then  reaches  upward,  covering  in 
the  back  and  sides  of  the  bladder  until  its  top  is  attained, 
from  which  point  it  is  continued  on  to  the  anterior  abdomi- 
nal wall.  The  cavity  between  the  rectum  and  bladder  is 
the  rectovesical  fossa.  The  peritoneal  folds  formed  around 
the  rectum  and  bladder  are  termed  the  ligaments  of  those 
organs. 

In  the  female  the  condition  is  altered  by  the  interposition 
of  the  uterus  and  vagina  between  the  bladder  and  the 
rectum. 

Posteriorly  the  peritoneum  reaches  as  low  as  the  upper 
part  of  the  vagina,  anteriorly  only  to  the  lower  part  of  the 
uterus.  The  hollow  behind  the  uterus  is  the  rectovaginal 
fossa,  Douglas's  pouch,  the  one  in  front  of  it  the  utero- 
vesical.      Laterally  from    the    uterus    the   peritoneal  folds 


478  A  MANUAL   OF  ANATOMY. 

called  the  broad  ligaments  pass  to  the  sides  of  the  pelvic 
cavity. 

Between  the  front  wall  of  the  bladder  and  the  inner 
surface  of  the  pubes  and  lower  abdominal  wall  is  a  space, 
not  covered  by  peritoneum,  called  the  space  of  Retzius. 

The  circuit  thus  traversed  outlines  the  cavity  of  the 
greater  peritoneum,  to  distinguish  it  from  the  cavity  of  the 
lesser  peritoneum  or  the  great  omentum.  Remember  that 
these  two  cavities  are  continuous  with  each  other,  but 
through  a  constricted  neck  which  is  called  the  foramen  of 
Winslo-w.  This  opening  lies  behind  the  gastrohepatic 
omentum,  opening  at  the  right  into  the  greater  cavity  just 
outlined,  and  continued  at  the  left  into  the  cavity  to  be 
examined.  A  finger  can  be  introduced  from  right  to  left, 
behind  the  gastrohepatic  omentum,  into  this  foramen. 

If  a  transverse  circuit  be  made  at  the  upper  part  of  the 
abdominal  cavity  the  peritoneum  will  be  seen  to  have  the 
following  arrangement  (Diag.  41): — 

It  will  be  easily  recognized  that  the  peritoneum  lines  the 
anterior  and  lateral  walls  of  the  abdomen.  It  will  also  be 
seen  to  cover  the  front  of  the  liver  (interrupted  by  the  fal- 
ciform ligament)  and  the  stomach,  and  that  it  connects 
these  organs  forming  the  anterior  layer  of  the  gastrohepa- 
tic omentum.  Continued  to  the  left,  the  peritoneum  turns 
around  the  fundus  of  the  stomach  and  passes  on  to  the 
spleen.  The  portion  of  the  peritoneum  between  the 
stomach  and  the  spleen  is  the  left  layer  of  the  gastrosplenic 
omentum.  From  the  spleen  the  peritoneum  extends  to 
the  back  of  the  abdominal  cavity,  forming  the  left  layer  of 
the  phrenosplenic  ligament  which  holds  the  spleen  in  place. 
The  fold  forming  the  last  ligament  turns  outward  and  covers 
the  abdominal  wall. 

Passing  to  the  right,  from  the  upper  surface  of  the  liver, 


Pig.  96.  A  Composite  Photograph  of  the  Abdominal  Wall  and  Viscera 
(Male).  [Subject  horizontal.] — A  photograph  of  the  exterior  of  the  abdomen  was 
taken  ;  then,  upon  the  same  plate,  a  photograph  of  the  abdominal  viscera  as  exposed 
without  moving  the  camera  or  subject.  Consult  in  this  connection  Figs.  87  (taken  be- 
fore) and  97  (taken  after  Fig.  96)  in  order  to  show  the  parts  more  sharply.— a,  a. 
Vertical  lines,  d.  Upper  horizontal  line,  c,  Lower  horizontal  line,  rf.  Umbilicus. 
I,  Left  lobe  of  liver.  2,  Stomach.  3,  Transverse  colon  showing  through  the  great 
omentum.  In  this  subject  the  great  omentum  whs  found  as  shown  in  the  figure.  4, 
Coils  of  small  intestine.  5,  Abdominal  wall.  6,  Inguinal  region — left  and  right. 
Notice  the  small  amount  of  viscera  in  this  region.  7,  The  hypogastric  region.  8, 
Falciform — suspensory — ligament  of  the  liver.  9,  Right  lobe  of  liver.  10,  Round 
ligament  in  free  margin  of  9.  11,  Ascending  colon  showing  one  of  the  longitudinal 
muscular  bands.  12,  Junction  of  the  caecum  and  vermiform  appendix.  13,  Ileum 
close  to  the  caecum. 


480  A  MANUAL   OF  ANA  TO  MY. 

the  peritoneum  is  seen  to  turn  around  to  its  under  surface, 
which  it  covers.  When  the  small  opening  of  the  foramen 
of  Winslow  is  reached  this  layer  becomes  continuous  with 
the  anterior  layer  already  described,  and  then  is  said  to 
"pass  through  the  foramen,"  forming  the  posterior  cover- 
ing for  the  liver  and  stomach  and  also  of  the  gastrohepatic 


Diag.  41.  A  Transverse  Section  in  the  Upper  Region  of  the  Abdomen. 
{Modified  front  Heatli's  Anatomy.)— I,  Stomach.  2,  Liver.  3,  Spleen.  4,  Pancreas. 
5,  Left  kidney.  6,  Aorta  at  the  coeliac  axis  and  its  three  branches.  7,  Inferior  vena 
cava.  8,  Right  kidney,  a,  Gastrohepatic  omentum,  b,  Cavity  of  great  omentum. 
c,  Gastrosplenic  omentum,  d.  General  peritoneal  cavity.  Arrow  indicates  its  com- 
munication through  foramen  of  Winslow  with  b. 


omentum.  (Remember,  we  are  now  within  the  cavity  of 
the  great  omentum  or  lesser  peritoneum.)  Passing  onward 
to  the  left,  this  layer  covers  in  the  posterior  wall  of  the 
stomach  and  turns  to  reach  the  spleen  (forming  the  right 
side  of  the  gastrosplenic  omentum),  then  from  the  spleen 
to  the  back  part  of  the  abdomen,  and  turning  to  the  right 
covers   the  structures    at   the  back  of  the  abdomen,  viz.  : 


F'2'  97-    Abdominal  Viscera  (Male).    [Subject  horizontalj— For  the  names 
of  the  exposed  parts  consult  the  preceding  photograph. 

31 


482 


A  MANUAL  OF  ANATOMY. 


the  pancreas,  aorta,  vena  cava  (forming  the  posterior  wall 
for  the  cavity  of  the  great  omentum),  and  extending  still 
to  the  right,  may  be  said  to  "  pass  through  the  foramen  of 
Winslow"  (forming  its  posterior  wall)  and  become  con- 
tinuous with  the  parietal  peritoneum  behind  the  right  lobe 
of  the  liver. 

A  transverse  tracing  at  a  lower  level  is  very  much  simpler 
and  can  be  easily  followed  from  the  diagram  42. 


Diag.  42.  A  Transverse  Section  in  the  Middle  Region  of  THt- abdomen. 
{After  Morris's  Anatomy.)— i,  Small  intestine.  2,  Descending  colon.  3,  Aorta.  4,  In- 
ferior vena  cava.    5,  Ascending  colon,    a,  Mesentery. 


The  Abdominal  Viscera  Covered  by  Peritoneum. 

The  stomach,  liver,  spleen,  first  portion  of  the  duodenum, 
all  of  the  small  intestine,  caecum,  vermiform  appendix, 
transverse  colon,  omega  loop,  first  part  of  the  rectum  (de- 
scribed in  two  parts),  the  ovaries.  Fallopian  tubes,  and  the 
uterus. 


The  Peritoneal  Fossae. 

In  the  lower  part  of  the  abdomen  is  found  the  fossa  between 


THE  ABDOMEJV,  INTERIOR.  483 

the  rectum  and  bladder  (male)  called  the  rectovesical.  In 
the  female  there  are  two  fossae  here,  one  between  the 
rectum  and  the  uterus  and  vagina, — the  rectovaginal  or 
the  pouch  of  Douglas — and  a  second  one  between  the  uterus 
and  the  bladder,  the  uterovesical. 

The  Intersigmoid  Fossa. — This  is  a  small  pouch — may- 
be large  enough  to  admit  a  ball  having  a  radius  of  two 
inches — located  in  the  middle  of  the  base  of  the  sigmoid 
mesentery  on  its  left  surface.  The  opening  of  the  fossa  is 
to  the  left  and  downward. 

Fossa  Duodenojejunalis. — This  pouch  will  admit  the 
"first  joint  of  the  thumb."  It  is  found  at  the  left  of  the 
vertical  or  last  portion  of  the  duodenum.  The  opening  is 
upward.  Into  these  last  two  pouches  a  portion  of  the  in- 
testine might  work  its  way,  thus  forming  a  retroperitoneal 
hernia. 

DISSECTION. 
Incise  the  anterior  layer  of  the  gastrocoUc  omentum  parallel  with  and  just 
below  the  greater  curvature  of  tlie  stomach.  This  will  open  into  the  cavity  of 
the  great  omentum.  The  hand  introduced  into  this  cavity  will  find  the  liver 
above,  the  stomach  in  front,  the  pancreas  and  colon  behind,  and  the  finger  can 
be  carried  to  the  right  behind  the  stomach  to  appear  through  the  foramen  of 
Winslow  behind  the  gastrohepatic  omentum.  The  peritoneum  lining  the  cavity 
of  the  greater  omentum  then  covers  the  posterior  surface  of  the  stomach  and 
first  part  of  the  duodenum,  becomes  blended  with  the  anterior  covering  of  the 
stomach  at  its  lower  border  as  already  stated,  then  loops  downward  to  form  the 
inner  layer  of  the  greater  omentum,  and  on  the  return  becomes  attached  to  the 
upper  (anterior)  surface  of  the  transverse  colon,  which  it  covers,  then,  passing 
backward  to  the  abdominal  wall,  forms  the  upper  layer  of  the  transverse  meso- 
colon. The  base  of  the  transverse  mesocolon  covers  in  the  duodenum  and 
pancreas.  From  this  point  the  peritoneum  extends  upward  to  the  under  sur- 
face of  the  diaphragm,  then  on  to  the  liver,  forming  the  posterior  layer  of  the 
coronary  and  lateral  ligaments  of  that  organ,  also  of  the  gastrophrenic  liga- 
ment. From  the  posterior  margin  of  the  stomach  the  anterior  and  posterior 
layers  of  peritoneum  pass  backward  to  enclose  the  spleen,  gastrosplenic  omen- 
tum, then  on  to  be  attached  to  the  posterior  abdominal  wall,  forming  the  spleno- 
phrenal  ligament. 


484  A  MANUAL   OF  ANATOMY. 

Suininary  of  the  Development  of  the  Viscera  and  Peri- 
toneum. 

(i)  The  alimentary  canal  is  first  undifferentiated  and  a 
straight  tube. 

(2)  It  is  attached  to  the  backbone  by  a  thin  membrane 
— the  primitive  peritoneum.  Also  for  its  upper  portion  to 
the  anterior  abdominal  Avail.      Diag.  32. 

(3)  As  development  proceeds  the  various  parts  of  the 
alimentary  canal  appear,  as  stomach,  duodenum,  small  in- 
testine, large  intestine  (colon,  omega  loop,  rectum). 

(4)  The  peritoneum  attached  to  these  various  parts  of  the 
intestinal  canal  receives  special  names  according  to  the  part 
to  which  it  is  attached,  as  mesogaster,  mesoduodenum, 
mesentery,  mesocolon,  sigmoid  mesentery,  mesorectum. 

(5)  As  the  alimentary  canal  grows  it  becomes  thrown  into 
loops,  the  greatest  lengthening  taking  place  in  the  part 
known  as  the  small  intestine.      Diag.  33. 

(6)  The  primitive  relations  are  destroyed  by  the  large 
intestine  crossing  over  to  the  right  side  of  the  abdominal 
cavity  in  front  of  the  small  intestine  (duodenum),  this 
brings  the  small  intestines  to  the  left  side  of  the  abdominal 
cavity. 

(7)  This  also  brings  out  new  attachments  for  the  mesen- 
tery of  the  large  intestine  (colon,  ascending  and  transverse). 

(8)  The  lower  (pyloric)  end  of  the  stomach  and  the  liver 
share  in  the  change  about,  by  falling  over  to  the  right  side 
of  the  abdominal  cavity,  while  the  spleen  and  the  upper 
(cardiac)  end  of  the  stomach  turn  to  the  left.  Similarly,  the 
head  of  the  pancreas  turns  to  the  right,  while  its  tail  points 
to  the  left.      Diags.  34,  35. 

(9)  The  liver  is  developed  between  the  folds  of  the  an- 
terior mesogaster,  passing  from  the  anterior  border  of  the 
stomach    to   the    diaphragm.      It   is    connected    with    the 


THE  ABDOMEN,  INTERIOR.  485 

duodenum  by  its  duct,  which  opens  into  this  part  of  the 
bowel. 

The  pancreas  arises  from  budding  cells  posterior  to  the 
duodenum  and  between  the  two  layers  of  the  mesoduode- 
num  ;  its  duct  opens  into  that  of  the  bile  duct. 

The  spleen  arises  posterior  to  the  stomach,  and  also  be- 
tween the  two  layers  of  the  mesogaster. 

(10)  After  the  rotation  of  the  intestines  and  the  change 
to  the  oblique  position  by  the  stomach,  the  great  omentum 
is  formed  by  the  pouching  of  the  mesogaster,  below  the 
spleen  and  as  far  as  the  first  part  of  the  duodenum,  to  the 
left  and  forward,  to  form  a  bag  that  hangs  down  in  front  of 
the  rest  of  the  intestines.      Diags.  36,  37. 

(11)  In  the  formation  of  the  great  omentum,  the  attach- 
ments of  the  primary  mesogaster  and  transverse  meso- 
colon are  altered,  until  the  great  omentum  seems,  in  the 
adult,  to  come  from  the  lower  border  of  the  stomach  to 
the  anterior  border  of  the  colon,  having  looped  down  to 
form  the  apron.  Consequently  there  is  only  one  process 
of  peritoneum  which  forms  the  posterior  attachment  of  the 
great  omentum,  and  it  is  between  the  folds  of  this  the  great 
omentum  that  the  colon  is  situated,  and  the  part  of  the 
great  omentum  passing  to  the  backbone  is  called  the  trans- 
verse mesocolon.     Diags.  38  and  40. 

(12)  If  the  fcEtal  form  remains  throughout  life  the  pos- 
terior fold  of  the  omentum  returns  to  the  backbone  for  a 
separate  attachment  above  the  attachment  of  the  meso- 
colon.     Diag.  37. 

The  description  of  the  abdominal  viscera  will  be  brief 
and  only  include  the  gross  anatomy.  The  descriptions  will 
also  be  given  consecutively,  and  their  dissection  later.  This 
is  to  avoid  unnecessary  repetition. 


486  A  MANUAL   OF  ANA  TOMY. 

The  dissector  is  expected  to  first  read  the  descriptions 
and  then  to  expose  the  organs  according  to  the  plan  as 
given  later,  identifying  as  he  goes  the  main  points  regarding 
each  organ. 

Too  much  stress  cannot  be  given  to  the  study  of  the 
intimate  and  projected  surface  relations  of  the  various 
organs  of  the  abdominal  cavity.  Every  year  sees  surgeons 
successfully  invading  new  fields,  hitherto  forbidden  ground  ; 
in  the  last  few  years  no  part  of  surgery  has  yielded  more 
brilliant  results  than  in  the  domain  of  the  abdomen. 

The  student  is  urged  to  do  more  than  to  casually  identify 
the  main  abdominal  relations  ;  he  is  to  study  for  himself  the 
position  of  each  and  every  organ  without  reference  to  what 
may  be  written  about  it.  Read  what  has  been  said,  then 
study  and  think  for  himself.  He  will  find  there  are  many 
surprises  in  store  for  him  if  he  studies  in  this  way. 

The  Liver.     Figs.  96,  97,  104,  105,  108,  109. 

Position  and  Size. — The  liver  occupies  the  dome-shaped 
space  under  the  diaphragm  on  the  right  side,  reaching 
across  the  middle  line  a  distance  of  two  and  one-half  inches. 
It  is  the  largest  gland  in  the  body,  weighing  about  three 
and  one-half  pounds.  It  measures  twelve  inches  from  side 
to  side,  six  and  one-half  from  before  backward,  and  three  and 
one-half  vertically  in  its  thickest  part  (in  the  right  lobe). 

The  Ligaments. — The  liver  is  held  in  position  by  five 
ligaments,  all,  except  the  round,  derived  from  the  periton- 
eum which  encloses  almost  the  entire  gland,  and  all  (with 
the  same  exception)  attached  to  the  diaphragm. 

( I )  The  suspensory,  falciform,  or  broad  ligament  is  the 
first  one  seen  on  opening  the  abdomen.  It  is  attached  to 
the  right  of  the  middle  line  from  the  umbilicus  backward  to 
the  posterior  part  of  the  diaphragm,  and  below  to  the  liver. 


# 


■•^^s:S^ 


^f^ 


Fig.  98.  Abdominal  Regions  (Female).  [Subject  horizontal.]— For  the  names 
of  the  various  regions  consult  Fig.  87.  This  photograph  should  be  used  in  connec- 
tion with  the  following  photographs  to  determine  the  visceral  surface  relations. 


488  A  MANUAL   OF  ANATOMY. 

dividing  the  gland  into  the  right  (larger)  and  left  (smaller) 
lobes. 

(2)  In  the  free  margin  of  the  suspensory,  is  the  round 
ligament,  a  fibrous  cord  representing  the  umbilical  vein.  It 
extends  from  the  umbilicus  to  the  under  surface  of  the 
liver,  and  disappears  in  the  umbilical  fissure. 

(3)  Extending  from  side  to  side,  at  right  angles  to,  and- 
continuous  with,  the  suspensory  ligament,  is  the  coronary 
lig-ament. 

(4,  5)  The  extreme  ends  of  the  coronary  ligament  are 
called  the  right  and  left  lateral  lig-aments. 

Relations. — The  liver  will  be  seen  to  be  in  relation  with 
the  following  organs.  (Not  all  will  appear  at  this  stage, 
but  as  before  remarked,  they  are  given  here  consecutively, 
and  later  may  be  confirmed  or  disproved)  : — 

Above,  the  upper  surface  lies  against  the  diaphragm. 
Below,  the  lower  surface  comes  in  contact  with  the  hepatic 
flexure  of  the  colon,  gall  bladder  (part  of  the  liver), 
stomach  (cardiac  and  pyloric  ends  and  anterior  surface), 
the  first  and  second  parts  of  the  duodenum,  the  right 
kidney,  and  the  gastrohepatic  omentum.  Behind,  the  dia- 
phragm and  its  crura,  the  tenth  and  eleventh  dorsal  verte- 
brae, the  oesophagus,  the  aorta  (separated  from  the  liver  by 
the  diaphragm),  vena  cava,  and  the  right  suprarenal  body. 

Surfaces,  Lobes,  and  Fissures. — (i)  The  upper  sur- 
face is  convex  to  fit  in  the  concavity  of  the  diaphragm,  and 
is  divided  by  the  suspensory  ligament  into  the  right  and 
left  lobes. 

(2)  The  lower  surface  is  generally  concave,  and  is  sepa- 
rated from  the  posterior  by  the  transverse  fissure.  Into 
the  transverse  fissure  pass  the  portal  vein,  hepatic  artery, 
and  hepatic  nerves,  coming  out  of  the  hepatic  duct. 

The  right  lobe  is   divided   from   the  left,  by  the   longi- 


Fig-  99'  Abdominal  Viscera  (Female).  [Subject  horizontal.]— a,  Stomach. 
b.  Liver,  c.  Falciform  ligament  of  the  liver,  in  the  free  (right)  margin  of  which  is  the 
round  lia;ament.  d.  The  coils  of  small  intestines.  The  photograph  shows  the  exact 
condition  that  was  found  on  opening  the  abdomen.  The  great  omentum  was  out  of 
sight,  being  rolled  up  under  the  stomach. 


490  A  MANUAL   OF  ANAT03IY. 

tudinal  fissure.  This  fissure  consists  of  two  parts  ;  the 
anterior  (the  "umbilical),  in  which  the  umbilical  vein  lies  ; 
and  the  posterior  for  the  ductus  venosus,  a  venous  trunk 
which  joins  the  umbilical  vein  to  the  vena  cava  (by  way  of 
a  hepatic  vein).  These  veins  are  foetal  structures.  The 
gall  bladder  occupies  a  shallow  hollow — the  fissure  of  the 
gall  bladder.  Between  the  fissures  for  the  umbilical  vein 
and  the  gall  bladder,  is  the  quadrate  lobe,  bounded  behind 
by  the  transverse  fissure  and  in  front  by  the  anterior 
border  of  the  liver.  The  quadrate  lobe  is  often  connected 
to  the  left  over  the  umbilical  fissure  forming  the  pons 
hepatis. 

The  lower  surface  of  the  liver  shows  several  slight  de- 
pressions produced  by  contact  with  the  various  abdominal 
organs  beneath  it ;  these  are  called  impressions.  They  are 
for  the  stomach,  hepatic  flexure,  duodenum,  and  right 
kidney. 

(3)  The  posterior  surface  is  poorly  marked.  It  may  be 
defined  as  that  part  of  the  liver  behind  the  transverse 
fissure.  It  is  deeply  concave  from  side  to  side  to  accom- 
modate the  spine  and  crura  of  diaphragm.  It  contains  a 
vertical  gutter  in  which  lies  the  vena  cava  inferior,  and 
called  the  fissure  for  the  vena  cava.  At  the  left  of  the 
vena  cava  is  the  Spigelian  lobe,  separated  from  the  left 
lobe  by  the  fissure  for  the  ductus  venosus. 

The  Spigelian  lobe  is  connected  with  the  right  by  a 
slender  tongue  or  ridge  of  liver  substance  known  as  the 
caudate  lobe. 

It  Avill  be  seen  that  the  fissures  of  the  liver  can  be  ar- 
ranged like  the  letter  "  H."  The  right  leg  is  made  up  of 
the  fissures  for  the  gall  bladder  and  vena  cava,  the  left  by 
the  umbilical  and  fissure  of  the  ductus  venosus,  the  cross 
bar  is  the  transverse  fissure. 


THE  ABDOMEN,  INTERIOR.  491 

The  anterior  border  is  thin  and  sharp,  and  is  notched 
at  the  umbilical  fissure.  To  the  right  of  this  notch  is  the 
fundus  of  the  gall  bladder.  If  distended  it  will  project 
beyond  the  liver  border. 

The  gall  bladder  (Figs.  104,  105)  is  a  membranous  sac 
situated  in  the  fissure  of  that  name,  used  as  a  reservoir  for 
the  bile.  Its  duct  is  the  cystic  duct  which  unites  with  the 
hepatic  to  form  the  common  bile  duct.  (For  the  course  of 
the  latter  see  GcxstroJicpatic  Oinciitiiiu.^ 

It  must  be  remembered  that  in  living,  healthy  people  the 
relations  of  the  abdominal  organs  to  each  other  and  to  the 
surface  of  the  body  varies  from  time  to  time  with  respira- 
tion, position  of  the  body  and  fullness  of  the  stomach,  and 
that  in  disease  the  variations  are  innumerable.  Conse- 
quently, all  measurements  are  only  relative,  and  true  for 
the  subject  and  at  that  particular  time.  However,  if  our 
measurements  are  not  exactly  correct  they  serve  to  give  us 
standards  from  which  to  note  variations.  Hence,  the  need 
that  every  student  should  investigate  for  himself  the  rela- 
tions of  the  subject  he  is  at  work  upon,  without  reference 
to  the  text-book  figures  ;  later  he  should  make  the  compari- 
son between  his  data  and  that  in  the  text-books. 

The  Surface  Area  of  Liver  Projection.  Figs.  96,  98,  108, 
109. — The  upper  border  of  the  liver  is  represented  by  a  line, 
beginning  two  and  one-half  inches  at  the  left  of  the  median 
line  on  a  level  with  the  sixth  left  sternochondral  articulation, 
and  drawn  slightly  downward  to  cross  the  sternum  at  the 
sternoxiphoid  articulation,  then  toward  the  right,  curved 
slightly  upward,  to  reach  a  point  one  inch  below  the  right 
nipple  ;  from  here  the  line  is  carried  directly  around  the 
chest  to  end  at  the  eighth  dorsal  vertebra. 

The  loii'er  liver  border  is  traced  by  an  oblique  line  start- 
ing at  the  left  over  the  eighth  costal  cartilage  (a  very  indefi- 


492  A  MANUAL   OF  ANA  TOMY. 

nite  point),  and  drawn  to  the  right,  crossing  the  middle  line 
of  the  body  midway  between  the  ensiform  and  the  umbili- 
cus, reaching  the  right  ninth  costal  cartilage  (another  blind 
point),  then  running  parallel  with  the  lower  margin  of  the 
thorax  to  the  eleventh  rib,  then  along  the  lower  border  of 
this  rib  to  the  spine. 

The  interlobidar  notch  is  half-way  between  the  right 
vertical  line  (see  page  435)  and  linea  alba.  The  fundus  of 
the  gall  bladder  lies  just  below  and  behind  the  tip  of  the 
cartilage  of  the  tenth  right  rib,  or  in  the  notch  between  the 
right  rectus  muscle  and  the  thoracic  margin.  The  cartilages 
given  above  are  "  areas"  not  "points,"  hence  considerable 
latitude  is  allowed. 

The  Gastrohepatic  Omentum.  Diag.  36,  No.  i.  Fig.  103. 
The  double  layer  of  peritoneum  which  extends  from  the 
transverse  fissure  and  under  surface  of  the  liver  to  the  upper 
border  of  the  stomach  and  first  portion  of  the  duodenum 
is  the  gastrohepatic  omentum.  It  consists  of  three  distinct 
parts  :  (i)  A  superior,  triangular  portion  of  a  dense  white 
ligamentous  structure, — the  tendinous  portion.  (2)  A 
middle,  oval  portion  opposite  the  lesser  curvature  of  the 
stomach.  This  segment  is  so  thin  that  it  is  easily  torn  and 
through  it  can  be  seen  the  Spigelian  lobe  of  the  liver, — the 
flaccid  part.  (3)  An  inferior  part  which  is  thick,  massive, 
and  at  the  right  ends  in  a  rounded  border  which  forms  the 
anterior  margin  of  the  foramen  of  Winslow.  In  this  free 
margin  are  the  hepatic  vessels  and  nerves.  The  vessels  are 
the  portal  vein,  hepatic  artery  and  duct.  The  duct  is  to  the 
right,  the  artery  to  the  left,  and  the  vena  porta  behind  the 
two.  (For  further  information  consult  a  careful  article  by 
Byron  Robinson,  on  the  Gastrohepatic  Omentum,  in  the 
i^.Y)  Medical  Record  iox  Kvig.  10,  1895.) 


Fig.  loo.    Abdominal  Viscera  (Female).      [Subject  horizontal.]— This  photo- 
graph shows  the  great  omentum  unrolled  and  spread  out  over  the  intestines. 


494  A  MANUAL  OF  ANA  TOMY. 

The  Stomach.      Figs.  96  to  100,  103,  104,  105. 

The  stomach  lies  on  the  left  side  of  the  abdomen,  below  the 
diaphragm  and  left  lobe  of  the  liver.  It  is  about  twelve 
inches  long,  four  inches  wide,  and  weighs  four  and  one-half 
ounces.  It  is  entirely  covered  by  peritoneum.  See  De- 
velopment, page  462.  Its  long-  axis  is  placed  obliquely 
from  above,  behind,  and  at  the  left,  to  downward,  forward, 
and  to  the  right. 

It  has  t-wo  opening's,  the  cardiac,  the  opening  of  the 
oesophagus  into  the  stomach,  and  the  pyloric,  the  beginning 
of  the  intestinal  canal.  There  is  no  constriction  about  the 
cardia,  but  around  the  pylorus  is  a  muscular  collar  forming 
a  sphincter. 

The  short  border,  or  the  lesser  curvature,  is  three  and 
one-half  inches  long  and  concave.  From  it  passes  the 
gastrohepatic  omentum  to  the  liver.  See  above.  From 
the  long-er  border,  or  the  greater  curvature,  hangs  down 
the  broad  peritoneal  apron,  the  greater  or  gastrocolic 
omentum. 

The  fundus  is  the  dilated  end  of  the  stomach  to  the  left 
of  the  cardia.  At  the  oesophagus  the  anterior  and  posterior 
layers  of  peritoneum  come  together  and  pass  on  to  the 
diaphragm,  forming  the  g-astrophrenic  ligament. 

To  the  right  along  the  lesser  curvature  these  layers  after 
joining,  form  the  gastrohepatic  omentum  and  continue  to 
the  liver,  while  below  from  the  greater  curvature  these  two 
layers  unite  to  form  the  great  omentum,  and  returning 
again  to  the  colon  may  also  be  called  the  gastrocolic 
omentum. 

Relations. — The  anterior  surface  is  in  relation  with  the 
liver,  diaphragm,  and  anterior  abdominal  wall.  The  area 
of  stomach  opposed  directly  to  the  abdominal  wall  is  re- 
presented by  a  triangle  formed  on  the  right  by  the  anterior 


THE  ABDOMEN,  INTERIOR.  495 

margin  of  the  liver,  on  the  left  by  the  margin  of  the  costal 
cartilages,  and  below  by  the  upper  horizontal  line.  See 
page  435. 

Behind,  the  posterior  surface  of  the  stomach  helps  to 
form  part  of  the  anterior  wall  of  the  cavity  of  the  great 
omentum  (lesser  peritoneum).  It  lies  in  front  of  the  pan- 
creas, great  vessels,  crura  of  diaphragm,  solar  plexus,  from 
all  of  which  it  is  separated  by  the  anterior  layer  of  the 
transverse  mesocolon,  also  in  front  of  the  spleen  and  the 
gastrosplenic  omentum,  the  splenic  artery,  left  kidney  and 
suprarenal  body.  Above,  are  the  liver,  gastrohepatic 
omentum,  diaphragm,  and  oesophagus.  Below,  the  gastro- 
colic or  greater  omentum,  transverse  colon  and  its  meso- 
colon. 

TJic  Surface  Area  of  the  Stomach  Projection. — The  stomach 
being  one  of  the  most  movable  organs  by  reason  of  its  loose 
peritoneal  connections  and  from  the  varying  states  of  dis- 
tention or  emptiness,  it  follows  that  to  attempt  to  give  any 
fixed  outlines  of  its  position  is  almost  useless.  The  cardiac 
end  is  the  only  point  that  can  be  fixed  with  any  degree  of 
exactness.  This  lies  behind  the  seventh  costal  cartilage, 
one  inch  to  the  left  of  the  sternum.  The  fundus  rises  up 
behind  and  above  the  location  of  the  apex  of  the  heart,  to 
the  level  of  the  sixth  costochondral  articulation. 

The  pylorus  is  the  most  uncertain  portion  ;  usually  it  is 
found  one  inch  to  the  right  of  the  median  line  and  two  inches 
below  the  ensiform. 

The  upper  border  will  be  indicated  by  a  short  curve,  with 
concavity  upward,  connecting  the  cardiac  and  pyloric  ori- 
fices. The  greater  curvature  is  drawn  upward  from  the 
cardia  to  the  point  reached  by  the  fundus,  then  with  a  wide 
curve  is  drawn  outward,  to  the  left  and  downward,  then  to 
the  right  and  after  crossing  the  middle  line  midway  between 


496  A  MANUAL   OF  ANATOMY. 

the  ensiform  and  umbilicus  the  border  is  curved  upward  to 
the  lower  part  of  the  pylorus. 

If  the  lower  border  of  the  stomach  reaches  below  the 
umbilicus  the  case  is  one  of  pathological  distention. 

The  stomach  is  entered  through  the  triangle  above  given. 
The  incision  may  be  parallel  with  the  costal  margin  or 
through  the  semilunar  line. 

The  Intestine. 

The  intestine  is  the  alimentary  canal  below  the  stomach. 
It  is  divided  into  the  small  and  large  intestine.  The  small 
intestine  consists  of  the  duodenum,  the  jejunum,  and  the 
ileum.  The  large  intestine  is  divided  into  the  caecum,  as- 
cending, transverse,  and  descending  colon,  the  omega  loop 
(sigmoid  flexure),  and  rectum. 

The  Duodenum.  Figs.  103,  104,  105. — Though  this 
portion  of  the  intestine  is  one  of  the  last  to  be  dissected,  it 
will  be  described  now  along  with  the  rest  of  the  intestine. 
The  duodenum  comprises  the  first  ten  inches  of  gut  below 
the  pylorus,  and  is  about  two  inches  in  diameter.  It  is 
divided  into  four  portions,  the  proximal  ascending  part, 
two  inches  long  ;  the  descending  portion,  two  and  three- 
fourths  inches  long ;  the  transverse  portion  four  to  five 
inches  long  ;  and  the  distal  ascending  portion,  one  inch  in 
length.  The  duodenum  is  the  only  fixed  portion  of  the 
small  intestine.  Its  adult  position  is  secured  through  the 
rotation  of  the  gut  in  the  foetus  (see  page  462),  by  which 
the  duodenum  is  crowded  to  the  back  of  the  abdominal 
cavity  by  the  transverse  colon  which  passes  in  front  of  it. 

(i)  The  proximal  ascending-  part.  This  is  two  inches 
long,  passes  upward  to  the  right  and  ends  opposite  the  neck 
of  the  gall  bladder.  It  is  enclosed  by  peritoneum  pro- 
longed from  the  stomach,  and  is  freely  movable. 


Fig.  loi.  Abdominal  Viscera  (Female).  [Subject  horizontal.!— The  small 
intestines  have  been  removed,  the  large  intestine  inflated,  and  the  great  omentum 
turned  up  over  the  thorax,  a.  End  of  duodenum  and  beginning  of  jejunum,  b,  End 
of  ileum.  The  intervening  portion  of  jejunum  and  ileum  has  been  removed,  c.  Caecum. 
The  point  of  junction  of  ileum  and  colon  is  well  shown  and  should  be  referred  to  tiie 
surface  by  consulting  Fig.  98.  d.  The  point  of  junction  of  the  vermiform  appendix 
with  the  caecum.  In  this  case  the  process  hung  loosely  down  into  the  pelvic  cavity. 
e.  Ascending  colon  passing  up  behind  a  flexure  of  the  transverse  colon,  f,  The 
hepatic  flexure.  ^,  ^,  Transverse  colon.  A,  Splenic  flexure,  t,  f,  Descending  colon. 
jtj>j>  Omega  loop,     k.  Rectum.     /,  /,  Great  omentum. 


32 


498  A  MANUAL  OF  ANA  TOMY. 

Relations. — Above  and  in  front,  liver,  gall  bladder,  fora- 
men of  Winslow.  Below,  pancreas.  Behind,  the  common 
bile  and  pancreatic  duct,  and  vessels  passing  to  the  liver. 

(2)  The  descending-  portion  is  two  and  three-fourths 
inches  long,  and  extends  from  the  neck  of  the  gall  bladder 
to  the  level  of  the  second  or  third  lumbar  vertebra. 

Relations. — Front,  transverse  colon  and  mesocolon.  To 
the  left,  pancreas.  To  the  left  and  posterior,  the  common  bile 
duct.    Behind,  the  right  kidney,  renal  vessels,  and  vena  cava. 

This  portion  of  the  duodenum  is  covered  only  in  front  by 
the  peritoneum.  Into  this  part  of  the  duodenum  the  com- 
mon bile  and  pancreatic  duct  opens,  at  a  point  four  inches 
from  the  pylorus. 

(3)  The  third  or  transverse  portion  of  the  duodenum, 
four  or  five  inches  long,  is  the  most  fixed  portion  of  the 
alimentary  canal.  It  crosses  the  spine  over  the  second  or 
third  lumbar  vertebra,  in  a  slightly  oblique  direction,  the 
right  end  being  a  little  lower  than  the  left. 

Relations. — In  front,  it  is  covered  by  the  peritoneum, 
transverse  colon  and  mesocolon,  and  the  superior  mesen- 
teric artery.  Above,  the  pancreas,  inferior  pancreaticoduo- 
denalis  artery,  the  superior  mesenteric  artery  and  vein. 
Behind,  the  crura  of  the  diaphragm,  vena  cava,  aorta. 

(4)  The  fourth  or  distal  ascending-  portion,  usually 
described  as  a  part  of  the  third  portion.  This  part  is  only 
one  inch  long,  curves  vertically  upward,  is  nearly  covered 
by  peritoneum.  It  is  held  in  position  by  a  process  of  peri- 
toneum containing  some  muscular  fibres  and  called  the 
musculus  suspensorius  duodeni  (of  Treitz),  which  extends 
from  the  left  crus  of  the  diaphragm  and  tissues  about  the 
cceliac  axis.  Behind  this  band  is  the  small  fossa  duo- 
denojejunalis,  opening  upward,  and  into  which  a  retro- 
peritoneal hernia  might  possibly  find  its  way. 


THE  ABDOMEN,  INTERIOR.  499 

The  Small  Intestine.      Figs.  96  to  lOO. 

The  first  two-fifths  of  the  intestine  below  the  duodenum 
is  called  the  jejunum,  the  remaining  three-fifths,  the  ileum. 
The  coils  of  the  small  intestine  fill  in  the  space  left  by  the 
arching  colon  at  the  sides  and  above,  and  the  pelvic  viscera 
below.  They  are  attached  to  the  posterior  abdominal  wall 
by  the  mesentery,  a  double  layer  of  peritoneum,  which 
reaches  from  the  left  side  of  the  second  lumbar  vertebra  to 
the  right  iliac  fossa,  a  distance  of  four  to  six  inches.  The 
mesentery  is  about  eight  or  nine  inches  in  width,  and  in 
length  along  its  intestinal  border  equals  the  jejunum  and 
ileum.  Between  the  layers  of  the  mesentery  the  superior 
mesenteric  artery  ramifies.  Sometimes  a  remnant  of  the 
vitello-intestinal  duct  is  found  on  the  outer  border  of  the 
ileum  at  a  distance  of  from  one  to  three  feet  from  the  ileo- 
caecal  valve  ;  if  present  it  is  called  Meckel's  diverticulum. 
When  existing  it  may  be  a  menace  to  the  individual  on  ac- 
count of  forming  adhesions  with  some  other  part  of  the 
abdomen,  thus  forming  a  band  or  bridge  over  or  under 
which  a  portion  of  the  intestine  might  become  constricted. 
In  the  normal  subject  it  will  be  seen  that  the  mesenter}^  is 
just  short  enough  to  keep  the  margin  of  the  intestine  from 
engaging  in  the  abdominal  rings  or  femoral  opening,  con- 
sequently in  hernia  the  mesentery  must  be  abnormally 
elongated  congenitally  or  by  acquisition. 

The  ileum  joins  the  large  intestine  in  the  right  inguinal 
region,  at  right  angles  to  the  larger  gut,  and  from  two  to 
three  inches  from  its  lower  blind  extremity. 

The  small  intestine  opens  by  a  valvular  orifice,  the  ileo- 
csecal  valve,  into  the  larger.  This  opening  is  behind  a 
line  joining  the  anterior  superior  iliac  spine  and  the  um- 
bilicus, and  at  a  distance  of  three  inches  from  the  first 
point. 


500  A  MANUAL   OF  AAA  TO  MY. 

The  Large  Intestine.      Figs.  96,  97,  98,  lOl,  102. 

Reaches  from  the  right  inguinal  region,  upward  and 
across  the  abdomen,  then  descends  along  the  left  side,  to 
pass  into  the  pelvic  cavity. 

It  has  a  length  of  five  and  one-half  feet,  and  a  diameter 
of  two  inches. 

The  large  intestine  is  not  only  larger  than  the  small,  but 
is  distinguished  from  it  by  pendent  masses  of  fat  covered  by 
peritoneum — appendices  epiploiccE,  and  by  having  three  bands 
of  muscular  tissue  longitudinally  disposed  upon  its  exterior, 
one  posteriorly  at  the  mesenteric  attachment,  one  anteriorly, 
and  one  internally.  These  bands  being  shorter  than  the 
bowel  give  it  a  saccidated  appearance. 

Its  blind  extremity,  below  the  junction  of  the  ileum,  is 
the  caecum. 

The  caecum  lies  in  the  right  lumbar  or  inguinal  region. 
It  is  about  two  and  one  half  inches  long  and  about  three 
inches  wide.  From  its  lower,  posterior  surface  the  vermi- 
form appendix  comes  off,  and  lies  usually  in  a  direction  up- 
ward and  to  the  left,  but  often  the  appendix  may  hang  down 
into  the  pelvic  cavity,  or  take  any  other  position  about  the 
lower  end  of  the  caecum.  The  caecum  and  appendix  are  usu- 
ally entirely  enclosed  by  peritoneum  (the  appendix  having 
a  distinct,  though  small  mesentery),  and  are  free  within  the 
abdominal  cavity,  consequently  any  pus  coming  from  the 
interior  of  either  would  be  discharged  into  the  general 
abdominal  cavity  and  start  up  a  (usually)  fatal  peritonitis, 
unless  the  exudation  is  shut  off  by  inflammatory  adhesions 
agglutinating  the  adjacent  intestines  together,  to  form  a 
local  pus  cavity. 

The  point  at  which  the  appendix  joins  the  caecum  is  on 
the  ilio-umbilical  line  (from  anterior  superior  spine  of  ilium 
to  umbilicus)  at  a  distance  from  the  iliac  spine  of  two  and 


THE  A  B  DOM  EX,  INTERIOR.  501 

one-half  inches.  As  it  is  at  this  point  that  the  pain  is 
usually  greatest  in  appendicitis,  it  is  a  good  point  to  keep 
in  mind.  As  it  was  first  mentioned  by  McBurney  it  takes 
the  name  of  that  surgeon  and  is  called  McBurney's  point. 

From  the  caecum  to  the  liver  the  large  intestine  is  called 
the  ascending-  colon.  Here  taking  a  sudden  bend  to  the 
left  the  bowel  becomes  the  transverse  colon,  and  the  bend 
is  the  hepatic  flexure. 

On  the  left  side  of  the  body,  under  the  spleen,  the  gut 
turns  downward  to  form  the  descending-  colon  while  the 
bend  is  called  the  splenic  flexure.  The  continuation  of 
the  large  intestine  is  the  omega  loop  and  rectum. 

The  ascending  colon  (Figs.  96,  97,  98,  lOi,  102)  is 
usually  only  enveloped  by  peritoneum  in  front  and  at  the 
sides,  the  posterior  part  of  the  bowel  resting  against  the 
back  of  the  abdomen.  It  may,  however,  be  completely 
covered  by  peritoneum,  in  which  case  it  is  provided  with  a 
distinct  mesentery. 

Relations. — In  front  and  at  the  right  is  the  abdominal  wall, 
at  the  left  the  coils  of  small  intestine,  below  the  caecum,  and 
behind  the  quadratus  lumborum,  and  lower  portion  of  the 
right  kidney. 

The  hepatic  flexure  lies  up  under  the  overhanging  edge 
of  the  liver,  in  close  contact  with  the  gall  bladder.  From  its 
outer  border,  there  is  often  a  continuation  of  the  transverse 
mesocolon  to  the  side  of  the  abdomen  ;  upon  this  little  shelf 
the  right  extremity  of  the  liver  rests  (sustentaculum  hepatis). 

The  transverse  colon  (Figs.  96,  97,  98,  loi)  crosses  the 
abdomen  from  right  to  left,  and  from  the  hepatic  to  the 
splenic  flexure.  It  rises  higher  at  its  two  extremities  than 
in  the  middle,  where  it  crosses  the  middle  line  just  above 
the  umbilicus. 

Relations. — Above,  gall  bladder,  liver,  stomach.      Behind, 


502  A  MANUAL   OF  ANATOMY. 

the  third  portion  of  the  duodenum.  Below,  the  small  in- 
testine. In  front  it  is  covered  by  the  great  omentum. 
Its  mesentery  is  attached  to  the  posterior  abdominal  wall 
over  the  duodenum  and  pancreas,  it  passes  to  enclose  the 
colon  then  drops  downward  to  form  the  greater  omentum, 
then  rises  to  the  lower  border  of  the  stomach,  and  first  por- 
tion of  the  duodenum.     See  Diag.  40. 

The  splenic  flexure  is  in  contact  with  the  spleen  above. 
From  its  outer  margin  the  transverse  mesocolon  is  con- 
tinued to  the  under  surface  of  the  abdomen  over  the  tenth 
rib.  This  band  is  the  costocolic  ligament,  and  its  func- 
tion is  to  support  the  spleen  (sustentaculum  splenis). 

The  descending-  colon  (Figs.  98,  loi,  102)  extends  from 
the  splenic  flexure  to  the  left  iliac  fossa.  It  is  covered  in 
front  and  at  the  sides  by  peritoneum,  its  posterior  surface 
being  usually  in  contact  with  the  abdominal  wall.  But,  as 
with  the  ascending  colon,  this  part  of  the  colon  may  have 
a  distinct  mesentery.  In  this  case  the  peritoneal  cavity 
would  be  opened  in  performing  lumbar  colotomy  ;  if  there 
is  no  mesentery  the  gut  can  be  cut  into  without  invading 
the  general  peritoneal  cavity. 

Relations. — In  front  and  at  the  sides,  the  small  intestine. 
Behind,  the  diaphragm,  left  kidney,  quadratus  lumborum 
muscle. 

The  omega  loop,  or  sigmoid  flexure  (Figs.  96,  97,  98, 
10 1,  102),  is  the  next  part  of  the  bowel  below  the  descend- 
ing colon.  It  lies  in  the  left  iliac  fossa,  reaching  into  the 
pelvic  cavity  as  low  as  the  third  portion  of  the  sacrum,  in- 
cluding in  its  extent  the  so-called  first  portion  of  the  rectum, 
when  that  part  of  the  bowel  is  described  in  three  portions. 
Its  length  is  18  inches.  When  distended  the  apex  of  the 
loop  may  reach  over  to  the  right  so  far  as  to  come  in 
contact  with  the  caecum.     At  its  lower  end  it  is  provided 


I 


.,      A.M. 


Fig.  102.  Blood  Supply  TO  THE  Intestines.  [Subject  horizontal.]— i,  i,  Trans- 
verse colon.  2,  Superior  mesenteric  artery.  3,  Hepatic  flexure  of  colon.  4,  Right 
colic  artery.  5.  Ileocolic  artery.  6,  Caecum.  7,  Junction  of  the  vermiform  process 
with  caecum.  The  process  extends  downward  and  inward  behind  the  caecum.  8,  Great 
omentum.  9,  Longitudinal  muscular  band  on  the  large  intestine.  10,  Middle  colic 
artery.  11,  Splenic  flexure  of  colon.  12,  Left  colic  artery.  13,  Vasa  intestini  tenuis. 
14,  Duodenum,  transverse  portion.  15,  Sigmoid  artery.  16,  IDescending  colon.  17, 
Ileum  divided  close  to  the  caecum.  18,  Rectum.  19,  Omega  loop.  20,  Bladder.  The 
chain  of  arterial  anastomoses  upon  the  large  intestine  can  be  readily  followed.  Also 
the  secondary,  and  in  places  the  tertiary  arterial  loops. 


504  A  MANUAL  OF  ANATOMY. 

with  a  sort  of  sphincter,  formed  by  an  increase  in  the  circular 
fibres,  and  a  narrowing  ni  the  calibre  of  the  bowel.  The 
omega  loop  lies  normally  within  the  pelvic  cavity.  The  loop 
has  a  distinct  mesentery  and  is  freely  movable,  being  sur- 
rounded almost  entirely  by  peritoneum. 

The  attachment  of  the  omega  mesentery  crosses  the 
psoas  at  right  angles,  the  iliac  vessels  at  their  bifurcation, 
and  curves  downward  into  the  pelvis  toward  the  right  so  as 
to  reach  the  median  line.  This  line  of  attachment  meas- 
ures about  three  and  one-half  inches,  and  the  mesenteiy  is 
about  the  same  in  width. 

Relations. — With  the  small  intestines  in  front  and  to  the 
inner  side.  With  the  caecum  and  vermiform  appendix  (if 
distended)  on  the  right.  With  the  iliacus  and  psoas,  genito- 
crural  nerve,  iliac  vessels,  first  portion  of  sacrum  behind. 
Below  it  rests  upon  the  bladder  and  rectum  and  in  the 
female,  upon  the  uterus. 

The  rectum  (Figs,  no,  in),  is  the  last  portion  of  the 
large  intestine  from  the  end  of  the  omega  loop  at  the  third 
portion  of  the  sacrum  to  the  anus,  and  measures  about 
five  inches.  It  may  conveniently  be  described  in  two  por- 
tions. The  first  portion  three  and  one-half  inches,  from  the 
third  portion  of  the  sacrum  to  the  tip  of  the  coccyx.  This 
part  of  the  rectum  is  covered  by  peritoneum  only  upon  its 
front  and  at  the  very  beginning.  In  front  of  this  portion 
are  the  bladder,  seminal  vesicle,  trigone,  posterior  surface 
of  the  prostate.  In  the  female,  with  the  posterior  surface 
of  the  cervix  of  the  uterus  and  upper  part  of  the  vagina. 
Behind,  it  rests  upon  the  lower  part  of  the  sacrum  and  the 
coccyx  conforming  to  the  sacral  curve. 

The  peritoneum  is  reflected  from  the  rectum  to  the 
bladder  or  the  vagina,  and  in  the  bottom  of  this  reflection 
is  the  rectovesical  or  rectovaginal  fossa. 


THE  ABDOMEN,  INTERIOR.  505 

In  rectal  operations  it  is  important  to  know  how  far  the 
peritoneum  is  from  the  seat  of  operation.  Posteriorly  the 
peritoneum  is  at  a  distance  of  five  inches,  anteriorly  of  three 
inches  from  the  anus.     The  second  portion,  see  page  421. 

TJic  Surface  Area  of  the  Intestines. — The  abdomen  is 
divided  into  regions  as  indicated,  page  435. 

The  caecum  occupies  the  right  lumbar  region ;  it  is 
usually  located  in  the  text-books  in  the  inguinal  region, 
but  this  places  it  too  low  ;  it  may  reach  to,  but  not  often 
below,  the  lower  horizontal  line  (see  page  435),  and  lying  in 
the  upper  portion  of  the  right  iliac  fossa. 

The  appendix  joins  the  caecum  at  a  point  on  the  ilio- 
umbilical  line  two  and  one-half  inches  from  the  iliac  end,  or 
where  this  line  is  crossed  by  the  right  vertical. 

The  ileocaecal  valve  is  three  inches  from  the  iliac  spine  on 
the  ilio-umbilical  line. 

The  ascending  colon  reaches  upward  through  the  right 
lumbar  region  to  a  little  above  the  anterior  li\'er  border. 

The  hepatic  and  splenic  flexures  are  situated  in  the  right 
and  left  lumbar  and  hypochondriac  regions  ;  when  the  upper 
horizontal  line  is  drawn  between  the  tips  of  the  tenth  ribs, 
these  flexures  may  not  reach  above  this  line,  if  so  they  lie 
within  the  lumbar  regions.  Between  these  flexures  the 
transverse  colon  extends,  looping  downward  to  just  above 
the  umbilicus. 

The  descending  colon  occupies  the  left  lumbar  region, 
while  the  omega  loop  describes  almost  a  circle  from  the 
left  iliac  fossa  through  the  lower  left  portion  of  the  umbili- 
cal region  into  the  pelvis,  to  terminate  in  the  rectum 
behind  the  middle  line. 

The  operation  of  introducing  a  high  rectal  tube  is  some- 
times described.  If  the  rectum  and  omega  loop  is  exam- 
ined it  will  be  seen  that  it  is  impossible  to  pass   any  tube 


506  A  MANUAL  OF  ANATOMY. 

beyond  the  middle  of  the  loop  ;  if  the  tube  is  introduced 
still  further  the  bowel  is  carried  on  in  front  of  it,  and  if  too 
much  force  is  used  the  bowel  may  be  perforated,  as  has 
been  done,  and  death  follows. 

The  Spleen.      Fig.  105. 

The  spleen  is  an  oval  gland,  six  by  four  by  one  and  one- 
half  inches,  which  lies  behind  the  fundus  of  the  stomach. 
Its  long  axis  is  parallel  with  the  tenth  rib,  its  upper  border 
with  the  upper  edge  of  the  ninth  rib,  and  its  lower  border 
with  the  lower  edge  of  the  eleventh  rib. 

Its  inner  end  is  two  inches  from  the  left  of  the  middle 
line  behind,  and  its  outer  end  at  the  mid-axillary  line. 
It  is  covered  by  peritoneum  except  at  the  hilum  where  the 
vessels  and  nerves  are  situated. 

The  spleen  is  developed  in  the  mesogaster.  See  page 
467.  The  portion  of  the  primary  mesogaster  between  the 
stomach  and  spleen  is  now  called  the  g-astrosplenic  omen- 
tum, and  the  portion  of  the  mesogaster  extending  between 
the  spleen  and  diaphragm  is  now  called  the  phrenosplenic 
lig-ament.  Above,  the  latter  process  is  continuous  with  the 
gastrophrenic  ligament,  and  below,  the  former  passes  into 
the  left  portion  of  the  greater  omentum. 

The  splenic  artery,  vein,  lymphatics,  and  nerves  enter  or 
leave  the  spleen  at  the  hilum  of  the  spleen. 

Relations. — In  front,  stomach  and  splenic  flexure  of  the 
colon.  To  the  outside,  the  diaphragm,  inclusive  of  the 
ninth,  tenth,  and  eleventh  ribs.  To  the  inside,  the  stomach, 
pancreas,  left  kidney.  Below  the  spleen  rests  upon  the 
costocolic  ligament,  and  has  the  splenic  flexure  of  the  colon 
below  and  in  front. 

The  blood  supply  for  the  spleen  comes  from  the  splenic 
branch  of  the  coeliac  axis ;  the  splenic  vein  passes  to  unite 


7  8 


Fig.  103.  Dissection  of  Abdominal  Viscera  (Male).— a,  Stomach,  b,  Py- 
lorus, c.  Descending  Portion  of  duodenum,  d.  Transverse  portion  of  duodenum. 
e,  Beginning  of  vertical  portion  of  duodenum.  /,  Beginning  of  jejunum,  g-.  Ilio- 
psoas fascia,  h,  Bladder.  1,  Left  ureter.  2.  Cut  end  of  rectum.  3,  Left  superior 
vesical  artery.  4,  Psoas  magnus.  5,  Iliacus.  6,  Right  spermatic  vein.  7,  Vas 
deferens.  8,  Femoral  ring.  9,  .-V  transverse  line  formed  by  dividing  the  peritoneuia 
along  its  attachment  to  the  bladder.  In  front  of  this  line  the  bladder  is  uncovered  by 
the  peritoneum. 


508  A  MANUAL  OF  ANATOMY. 

with  the  superior  mesenteric  vein  behind  the  pancreas  and 
form  the  portal  vein. 

The  nerve  supply  is  from  the  solar  plexus. 

The  Pancreas.      Fig.    105. 

The  pancreas  is  an  elongated  gland  with  its  larger  ex- 
tremity (the  head),  within  the  duodenal  arch,  its  body  (the 
middle  portion)  crosses  the  spine  over  the  first  lumbar  ver- 
tebra, and  the  smaller  extremity  (or  the  tail)  is  in  contact 
with  the  spleen. 

Relations. — The  gland  lies  behind  the  peritoneum,  which 
forms  the  anterior  layer  of  the  transverse  mesocolon,  by 
which  the  gland  is  separated  from  the  stomach.  Behind, 
crura  of  the  diaphragm,  vena  cava,  aorta,  superior  mesen- 
teric artery  and  vein,  spine,  left  kidney  and  suprarenal  body. 
Above,  the  upper  border  rests  against  the  coeliac  axis  and 
has  the  splenic  artery  and  vein  running  behind  it.  Below, 
the  third  part  of  the  duodenum. 

The  duct  of  the  gland  opens  into  the  common  bile 
duct  close  to  the  duodenum  ;  it  is  called  the  duct  of 
"Wirsung-. 

The  blood-supply :  From  the  splenic,  hepatic,  and 
superior  mesenteric  arteries.  The  return  flow  is  through 
the  splenic  and  superior  mesenteric  veins. 

The  lymphatics  empty  into  the  superior  mesenteric 
glands. 

The  nerves  are  derived  from  the  solar  plexus  and  accom- 
pany the  arteries  to  the  gland. 

DISSECTION. 
Raise  the  liver  and  ribs  as  far  upward  as  possible  with  chain  hooks.      Draw 
the  stomach  downward.     Dissect  off  the   peritoneum   covering  the  hepatic 
artery,  duct,  and  portal  vein,  trace  the  artery  to  the  cceliac  axis,  and  the  gas- 
tric and  splenic  branches  of  the  same. 


THE  ABDOMEN,  INTERIOR.  509 

The  Coeliac  Axis.      Figs.    104,  105,  106. 

This  is  the  second  branch  of  the  abdominal  aorta.  It  is 
a  large  trunk  coming  off  the  front  of  the  abdominal  aorta 
just  after  it  comes  through  the  diaphragm. 

The  Solar  Plexus.       Figs.  74,  106,  107. 

About  the  cceliac  axis  will  be  found  the  semilunar  gang- 
lia, the  right  and  left,  joined  together  by  numerous  nerve 
filaments  composing  the  solar  plexus  (abdominal  brain). 
From  the  solar  plexus  nerves  pass  to  the  various  abdom- 
inal organs  with  the  blood  vessels.  They  form  secondary 
plexuses  upon,  and  take  the  names  of,  the  arteries  they 
accompany. 

The  Semilunar  Ganglia.     Figs.  74,  107. 

Are  irregularly  shaped  masses,  one  on  either  side  of  the 
cceliac  axis  and  superior  mesenteric  arteries. 

The  greater  and  lesser  splanchnic  nerves  are  formed 
within  the  thorax  (see  page  345)  ;  after  piercing  the  crus  of 
the  diaphragm  they  enter  the  upper  part  of  the  semilunar 
ganglion  to  take  part  in  the  formation  of  the  solar  plexus. 

Brandies  of  Cccliac  Axis. — The  coeliac  axis  divides  into 
the  gastric,  hepatic,  and  splenic  arteries. 

The  Gastric  Artery.      Figs.    104,  105. 

This  is  the  smallest  of  the  three  branches.  It  passes 
upward  to  the  left  to  reach  the  stomach  at  the  junction  of 
the  oesophagus,  then  turns  downward,  following  the  lesser 
curvature,  until  it  anastomoses  with  the  pyloric.  Its 
branches  are  {a)  oesophageal,  running  upward  to  the  oeso- 
phagus, to  anastomose  with  the  thoracic  oesophageal,  {p) 
the  branches  over  the  fundus,  to  unite  with  splenic  branches, 
{c)  terminal,  anastomosing  with  the  pyloric. 


510  A  MANUAL   OF  ANATOMY. 

The  Hepatic  Artery, 

Next  in  size,  comes  off  from  the  right  side  of  the  coeliac 
axis.    It  takes  a  direction  to  the  right  and  upward  to  the  liver. 

Brandies. — {a)  The  pyloric.  This  is  given  off  opposite 
the  pylorus,  passes  to  this  end  of  the  stomach,  turns  to  the 
left  and  joins  the  terminal  branches  of  the  gastric.  {8)  The 
g-astroduodenalis,  really  one  of  the  branches  of  bifurcation 
of  the  hepatic,  descends  behind  the  pylorus.  See  its  fur- 
ther course  below,  {c)  The  cystic.  This  supplies  the  gall 
bladder,  {d^  The  terminal  branches,  right  and  left,  to 
supply  their  respective  lobes  of  the  liver. 

The  relations  of  the  hepatic  artery,  duct,  and  portal  vein 

have  been  given.     See  Gastrohepatic  Omentum,  page  492. 

{e)  The  hepatic  gives  off  several  small  pancreatic  branches 

to  that  gland. 

DISSECTION. 
Divide  the  anterior  layer  of  the  greater  omentum  just  below  the  greater 
curvature  of  the  stomach.  Turn  the  stomach  up  over  the  chest  and  fasten  it 
there  with  chain  hooks.  Complete  the  dissection  of  the  splenic  and  gastro- 
duodenal  arteries.  Trace  the  common  bile  duct  and  portal  vein  as  far  as 
possible.  Clean  the  anterior  surfaces  of  the  pancreas,  duodenum,  and  the 
beginning  of  the  superior  mesenteric  artery. 

The  Splenic  Artery.  Fig.  105. — This  is  the  largest  of 
the  coeliac  branches.  It  passes  behind  the  stomach  toward 
the  left  to  supply  the  spleen.  It  gives  off  {a)  numerous 
small  branches  to  the  pancreas  as  it  courses  along  its  upper 
border,  called  the  pancreaticae  parvse.  (^)  A  large  artery, 
the  pancreatica  magna,  to  the  same  gland,  (r)  Then  the 
left  gastro-epiploic  which  follows  the  greater  curvature  of 
the  stomach  between  the  layers  of  the  great  omentum,  from 
left  to  right  to  inosculate  with  the  right  artery  of  this  name. 
{d^  The  vasa  brevia,  several  branches  to  the  fundus  of  the 
stomach,  which  anastomose  with  the  gastric,  {e)  The  ter- 
minal branches  to  the  spleen  itself. 


THE  ABDOMEN,  EXTERIOR.  511 

The  gastroduodenalis  will  be  seen  to  divide  into  two 
branches  :  the  right  gastro-epiploic,  which  courses  along 
the  greater  curvature  of  the  stomach  to  unite  with  the  left 
gastro-epiploic  ;  and  the  superior  pancreaticoduodenalis, 
which,  descending  in  the  interval  between  the  duodenum 
and  the  head  of  the  pancreas,  supplies  both  and  finalh'  an- 
astomoses with  the  inferior  pancreaticoduodenalis  from  the 
superior  mesenteric.  Both  gastro-epiploic  arteries  supply 
the  stomach  and  send  off  long  slender  branches  to  the 
omentum,  which  follow  backward  to  meet  similar  branches 
from  the  colic  arteries. 

These  branches  are  the  epiploic. 

The  Superior  Mesenteric  Artery.      Figs.  102,  105. 

Will  be  found  coming  out  between  the  pancreas  and  third 
portion  of  the  duodenum,  arising  from  the  front  of  the 
aorta.  It  gives  off  the  inferior  pancreaticoduodenalis, 
which  turns  to  the  left  between  the  pancreas  and  the  duo- 
denum, supplying  both,  and  terminating  by  anastomosing 
with  the  superior  artery  of  the  same  name. 

DISSECTION. 
Let  the  stomach  and  liver  drop  back  into  the  abdomen.  Raise  the  great 
omentum  and  transverse  colon  upward  on  to  the  chest  and  fasten  them  there. 
Dissect  off  the  presenting  layer  of  the  peritoneum  from  the  superior  mesenteric 
artery  and  its  branches.  It  will  not  be  necessary  to  clean  all  the  intestinal 
branches  to  their  distribution  ;  clean  their  origin,  and  trace  two  or  three,  with 
their  anastomoses,  to  the  smaH  intestine.  It  will  be  necessary  to  follow  all 
the  other  branches  coming  off  the  right  side  of  the  mesenteric.  They  are  the 
ileocolic,  the  right,  and  middle  colic. 

The  superior  mesenteric  arten,'  arises  from  the  front  of 
the  aorta  (as  previously  discovered),  above  the  transverse 
duodenum  and  below  the  pancreas.  It  takes  a  curved 
direction  downward  and  to  the  right  iliac  fossa. 

{a)   Its  first  branch  is  the  inferior  pancreaticoduodenalis. 


512  A  MANUAL  OF  AXA  TOMY. 

q.  V.  above,  (b)  From  the  convex  side  the  vasa  intestinl 
tenuis,  12  to  16  branches,  are  given  off  to  supply  the  small 
intestine  from  the  last  portion  of  the  duodenum  to  within  a 
short  distance  from  the  caecum.  These  intestinal  branches 
form  from  three  to  five  systems  of  arterial  anastomoses 
between  their  origin  and  distribution,  (c)  The  ileocolic 
supplies  the  last  portion  of  the  small  intestine  and  the 
beginning  (caecum)  of  the  large.  It  anastomoses  on  one 
side  with  the  last  intestinal  branch  and  on  the  other  with 
the  (d)  colica  dextra.  This  artery  is  distributed  to  the 
ascending  colon,  (e'^  The  colica  media  supplies  the  trans- 
verse colon.  These  last  three  arteries  form  long  arterial 
arches  from  one  to  the  other,  and  from  the  main  arches 
other  secondary  ones  are  formed  before  the  intestine  is 
finally  reached.  Along  with  the  arter}'  runs  the  vein,  only 
in  the  contrary  direction,  and  at  the  right  side  of  the  artery. 
The  vein  disappears  under  the  pancreas,  where  it  helps  to 
form  the  portal  vein.  See  page  514.  Its  tributaries  are 
the  right  gastro-epiploic,  pancreaticoduodenal  (superior  and 
inferior),  besides  the  veins  corresponding  to  the  branches  of 
the  superior  mesenteric  artery. 

DISSECTION. 
Tie  two  strong  strings  around  the  small  intestine  six  inches  from  the  duo- 
denum and  the  same  distance  from  the  caecum,  divide  the  intestine  between 
the  cords  at  both  points,  cut  it  away  from  its  mesentery,  and  remove  it  entirely. 
Clean  the  inferior  mesenteric  artery,  tracing  its  branches  to  the  descending 
colon,  omega  loop,  and  rectum. 

The  Inferior  Mesenteric  Artery.      Figs.   102,  105. 

Is  given  off  from  the  left  side  of  the  abdominal  aorta 
one  and  one-half  inches  above  its  bifurcation. 

Its  Brandies. 

(a)  The  colica  sinistra  supplies  the  descending  colon. 
(d)  The  sigmoid  is   distributed  to  the  sigmoid,  or  omega 


Fig.  104.  Dissection  of  Abdominal  Viscera  (Male).— a.  Stomach.  »,  Pylo- 
rus, c,  .\sceiiding  duodenum,  d.  Descending  duodenum,  e,  Transverse  duodenum. 
/,  Left  kidney,  i,  Gall  bladder.  2,  Round  ligament  of  liver  in  the  umbilical  portion 
of  the  longitudinal  fissure  of  liver.  Between  i  and  2  is  the  quadrate  lobe.  3,  Pons 
hepatis.  4,  Hepatic  artery  at  the  point  where  it  is  giving  oflF  the  gastroduodenal. 
5,  Abdominal  aorta.    6,  Gastric  artery. 


33 


514  A  MANUAL  OF  ANATOMY. 

loop,  ((f)  The  superior  hemorrhoidal  to  the  upper  part  of 
the  rectum.  These  arteries  form  a  chain  of  anastomoses 
with  one  after  the  other,  uniting  on  the  right  with  the  colica 
media,  and  below,  in  the  pelvis,  with  the  middle  hemor- 
rhoidal from  the  internal  iliac. 

The  long'est  arterial  arches  will  be  found  on  either  side 
of  the  colica  media. 

This  completes  the  arterial  supply  of  the  alimentary  canal 
from  the  oesophagus  to  the  middle  of  the  rectum. 

The  Inferior  Mesenteric  Vein 

Drains  the  blood  from  the  area  supplied  by  the  artery, 
passes  upward  at  the  left  of  the  artery  and  behind  the  peri- 
neum to  empty  into  the  splenic  vein  just  before  it  unites 
with  the  superior  mesenteric  vein  to  form  the  portal  vein. 

DISSECTION. 

Double  ligature  the  rectum,  and  divide  it.  Remove  the  large  intestine  en- 
tirely, carefully  cutting  through  its  peritoneal  attachments  close  to  the  bowel. 

Tie  a  cord  about  the  oesophagus  as  close  to  the  stomach  as  possible,  and 
divide  the  former  above  it.  Tie  two  cords  around  the  first  portion  of  the 
duodenum  and  divide  between  them.  Remove  the  stomach  and  spleen,  sev- 
ering their  ligaments  of  attachment  to  the  diaphragm  and  the  arteries  and 
veins  passing  to  and  from  them. 

Raise  the  duodenum  and  pancreas,  and  complete  the  dissection  of  the 
common  bile  duct,  the  pancreatic  duct,  from  where  it  joins  the  preceding  to 
a  distance  of  two  or  three  inches  into  the  gland,  the  portal  vein,  and  the 
tributaries  that  form  it. 

The  Portal  Vein.      Fig.  105. 

This  is  formed  behind  the  pancreas  by  the  junction  of  the 
superior  mesenteric  and  splenic  veins.  It  passes  upward 
toward  the  right  behind  the  first  part  of  the  duodenum  to 
the  transverse  fissure  of  the  liver.  It  is  about  three  inches 
long,  and  lies  between  the  two  layers  of  the  gastrohepatic 
omentum.      It  receives  the  pyloric,  gastric,  cystic,  the  supe- 


THE  ABDOMEN,  IXTERIOR.  515 

nor  mesenteric,  and  splenic.     See  Gastrolicpatic  Onicntuju, 
page  492. 

The  Splenic  Vein.      Fig.  105. 

Runs  in  company  with  the  arter}^  from  the  spleen  to  its 
junction  with  the  superior  mesenteric  to  form  the  portal 
vein.  Its  tributaries  are  the  vasa  brevia  veins,  left  gastro- 
epiploic, pancreatic,  and  inferior  mesenteric. 

DISSECTION. 

Draw  clown  the  liver,  carefully  sever  its  ligaments  until  the  vena  cava  is 
reached,  secure  room  enough  between  the  diaphragm  and  the  liver  to  pass  a 
ligature  around  the  vein,  tie  it,  and  divide  the  vein  below  the  ligature. 

Find  the  vena  cava  below  the  liver  and  ligate  it  there,  cutting  above  the 
ligature.  The  liver,  duodenum,  and  pancreas  can  now  be  removed  entirely, 
dividing  the  vessels  that  are  found  passing  to  them  and  the  peritoneal  pro- 
cesses which  bind  them  to  the  posterior  abdominal  wall,  remembering  to  keep 
close  to  the  viscera  that  are  being  removed. 

Clean  the  under  surface  of  the  diaphragm,  the  abdominal  aorta  and  its 
remaining  branches,  the  inferior  vena  cava  and  the  veins  emptying  into  it, 
the  suprarenal  bodies,  kidneys  and  their  blood  supply,  the  ureters,  the  sper- 
matic or  ovarian  arteries.     For  the  present  leave  the  pelvic  viscera. 

The  Abdominal  Aorta.      Figs.  74,  106,  107. 

Extends  from  the  aortic  opening  in  the  diaphragm,  over 
the  lower  margin  of  the  twelfth  dorsal  vertebra,  to  the 
lower  border  of  the  fourth  lumbar  vertebra,  where  it  divides 
into  the  two  common  iliac  arteries.  The  point  at  which  the 
aorta  bifurcates  is  a  little  below  and  to  the  left  of  the  um- 
bilicus. The  aorta  lies  at  first  in  front  of  the  vertebra,  but 
below  is  a  little  to  the  left. 

Relations. — In  front,  from  above  downward,  liver,  solar 
plexus,  gastrohepatic  omentum,  stomach  (at  the  oesopha- 
gus), anterior  layer  of  transverse  mesocolon,  vena  porta 
(or  ending  of  the  splenic  vein),  the  pancreas,  left  renal  vein, 
third  portion    of  the  duodenum,    mesentery,   small   intes- 


516  A  MANUAL  OF  ANATOMY. 

tines,  lymphatic  glands,  and  sympathetic  plexus.  Behind, 
the  aorta  rests  upon  the  lumbar  vertebrae  and  interverte- 
bral discs,  the  anterior  common  hgament  of  the  spine,  left 
crus  of  the  diaphragm,  and  left  lumbar  vein.  At  the  right, 
right  crus  of  diaphragm,  right  splanchnic  nerves.  Spigelian 
lobe  of  the  liver,  receptaculum  chyli,  vena  cava  inferior.  At 
the  left,  the  left  crus  of  the  diaphragm,  left  splanchnic 
nerves. 

The  Branches. 

( 1 )  The  inferior  phrenics.  These  arteries  may  arise  sepa- 
rately or  by  a  common  trunk  from  the  front  of  the  aorta  im- 
mediately after  the  aorta  appears  through  the  diaphragm,  or 
they  may  arise  from  the  coeliac  axis.  They  are  the  right  and 
left,  and  supply  the  right  and  left  sides  of  the  diaphragm. 
The  right  also  sends  small  branches  to  the  liver  and  right 
suprarenal  body,  the  left  to  the  oesophagus,  spleen,  and 
left  suprarenal  gland.  The  right  artery  passes  behind  the 
vena  cava. 

(2)  The  Coeliac  Axis,  see  page  509. 

(3)  The  right  and  left  suprarenal.  These  are  small 
arteries  that  come  off  the  side  of  the  aorta  and  supply  the 
suprarenal  bodies.  Besides  these,  the  suprarenal  glands 
receive  blood  from  the  inferior  phrenics  (superior  suprarenal 
blood  supply),  and  from  the  renals  (the  inferior  blood  sup- 
ply, the  suprarenals  themselves  being  the  middle  arteries). 

(4)  The  right  and  left  first  lumbar.     See  below. 

(5)  Superior  mesenteric.     Seepage  511. 

(6)  Right  and  left  renal.  Each  renal  artery  arises  from 
the  side  of  the  aorta,  on  a  level  with  the  first  lumbar  verte- 
bra, and  passes  outward  to  the  kidney,  breaking  up  into 
several  branches  to  enter  at  the  hilum  of  the  gland.  The 
artery  is  in  front  of  the  beginning  of  the  ureter  and  behind 
the  renal  vein. 


28.27 


Fig.  105.  Dissection  OF  Abdominal  Viscera  (Male).— a,  Stomach.  6,  Pylorus. 
c,  Ascending  duodenum  (when  stomach  is  in  natural  position),  d,  Descending  duo- 
denum, e.  Transverse  duodenum,  y,  Gall  bladder.  £■,  Spleen,  h,  Kidney,  i,  i,  i. 
Pancreas,  i,  Right  gastro-epiploic  artery.  2,  Hepatic  artery.  3,  Coeliac  axis.  4, 
Gastric  artery.  5,  Left  gastro-epiploic.  6,  Splenic  artery.  7,  Superior  mesenteric 
artery.  8,  Renal  vein.  9,  Ureter.  10,  Inferior  mesenteric  artery.  11,  Left  spermatic 
vein.  Trace  it  both  ways.  12,  Last  dorsal  nerve.  13,  Iliolumbar  artery.  14,  Ilio- 
hypogastric nerve.  1$,  Ilio-inguinal  nerve.  16,  External  cutaneous  nerve.  17,  Genito- 
crural  nerve.  18,  Gastroduodenal  artery.  19,  Superior  pancreaticoduodenal  artery. 
20,  Inferior  pancreaticoduodenal  artery.  21,  Inferior  vena  cava.  22,  Aorta.  23, 
Common  iliac  artery.  24,  Left  and  25,  Right  common  iliac  veins.  Notice  their  rela- 
tions to  their  corresponding  arteries.  2fi,  Obturator  nerve.  27,  External  iliac  artery. 
28,  Anterior  crural  nerve.     29,  External  iliac  vein.     30,  Middle  sacral  artery. 


518  A  MANUAL   OF  ANATOMY. 

The  right  artery  passes  behind  the  vena  cava,  and  is  a 
little  longer  than  the  left. 

(7)  The  right  and  left  spermatic.  Each  is  a  long,  slender 
artery  that  passes  with  the  spermatic  cord  through  the  in- 
ternal abdominal  ring,  the  inguinal  canal,  and  external  ring 
to  the  scrotum  as  far  as  the  testicle,  which  it  supplies.  The 
artery  lies  behind  the  peritoneum,  and  joins  the  cord  (vas 
deferens)  just  before  the  internal  abdominal  ring  is  reached. 

In  the  female  the  artery  is  the  ovarian,  and  supplies  the 
ovary  and  uterus.  It  has  the  same  origin,  and  course  until 
it  enters  the  broad  hgament  and  passes  to  supply  the  ovary 
and  uterus. 

(8)  The  right  and  left  second  lumbar  arteries.  See 
below. 

(9)  The  inferior  mesenteric.     See  page  512. 

( I  o)  The  right  and  left  third  lumbar.     See  below. 

(11)  The  right  and  left  fourth  lumbar. 

The  lumbar  arteries  arise  from  the  posterior  surface  of 
the  aorta,  opposite  the  bodies  of  the  lumbar  vertebrae,  pass 
outward  beneath  the  origin  of  the  psoas,  then  behind  the 
quadratus  lumborum,  finally  between  the  transversalis  and 
internal  oblique,  and  are  distributed  to  the  abdominal  wall 
as  far  forward  as  the  rectus  muscle,  anastomosing  with  the 
other  abdominal  arteries. 

(12)  The  right  and  left  common  iliacs.     See  below. 

(13)  The  sacra  media.  This  small  artery  arises  from 
the  posterior  surface  of  the  aorta  just  above  its  bifurcation, 
passes  down  in  front  of  the  middle  of  the  sacrum  to  the 
coccyx.  It  anastomoses  with  the  sacral  branches  from  in- 
ternal iliac  arteries. 

The  Common  Iliac  Arteries.      Figs.  103  to  107 

They  extend  from  the  bifurcation  of  the  aorta,  at  the 


THE  ABDOMEN,  INTERIOR.  519 

lower  border  of  the  fourth  lumbar  vertebra,  to  the  junction 
of  the  sacrum  and  ilium,  where  they  divide  into  the  external 
and  internal  iliacs. 

The  right  common  iliac  is  slightly  longer  than  the  left 
(right,  two  inches,  left  one  and  three-quarters).  They  are 
crossed  by  the  ureters  near  their  bifurcation,  and  in  the 
female,  by  the  ovarian  arteries. 

For  the  relation  to  the  corresponding  veins,  see  below. 

The  External  Iliac  Arteries.      Figs.  103  to  107. 

Continue  the  direction  of  the  common  iliac  arteries  from 
their  termination,  outward  beneath  Poupart's  ligament, 
where  they  become  the  femoral. 

Under  Poupart's  ligament  the  external  iliac  artery  is  at  a 
point  midway  between  the  anterior  superior  iliac  spine  and 
the  symphysis  pubis.  A  line  drawn  from  this  point  to  one- 
half  of  an  inch  below  and  at  the  left  of  the  umbilicus,  will 
indicate  the  course  of  the  common  and  external  iliac  arteries. 

The  external  iliac  is  crossed  by  the  vas  deferens  in  the 
male,  the  round  ligament  in  the  female,  and  by  the  deep 
circumflex  iliac  vein  in  both. 

For  relations  to  vein,  see  below. 

Brandies. 

(i)  The  deep  epig-astric.  See  page  456.  Figs.  94, 
103  to  107. 

(2)  The  deep  circumflex  iliac.  Figs.  106,  107.  Arises 
from  the  outside  of  the  external  iliac  and  takes  a  course 
outward,  following  the  direction  of  Poupart's  ligament  and 
the  crest  of  the  ilium,  to  anastomose  by  its  terminal 
branches  with  the  iliolumbar  artery. 

Its  muscular  branches  perforate  the  transversalis  muscle 
and  ascend  between  this  and  the  internal  oblique  muscles, 
supplying  the  abdominal  wall  and  anastomosing  with  the 


520  A  MANUAL   OF  ANATOMY. 

lower  intercostals,  lumbar,  and  lateral  branches  of  the  deep 
epigastric  arteries. 

The  External  Iliac  Veins.      Figs.  103,  104,  T05. 

They  begin  under  Poupart's  ligament,  as  the  continuation 
of  the  femoral  veins,  at  the  inside  of  the  external  iliac 
arteries. 

Each  passes  upward  along  the  inside  of  the  artery  to  ter- 
minate where  the  artery  begins  by  joining  with  the  internal 
iliac  vein  to  form  a  common  iliac  vein. 

The  left  vein  is  at  the  inner  side  of  the  artery  for  its 
entire  course,  and  posterior  to  the  artery.  The  right  vein 
starts  at  the  inner  side  of  the  artery  and  at  its  termination 
has  begun  to  pass  behind  it. 

Tributaries. — The  deep  epigastric,  and  circumflex  iliac 
veins,  which  collect  the  blood  from  the  area  suppHed  by 
the  arteries  of  the  same  names,  also  a  pubic  vein  which 
joins  the  obturator  and  external  iliac  veins. 

TJie  Internal  Iliac  Veins  will  be  given  later. 

The  Common  Iliac  Vein.     Figs.  103  to  106. 

Is  formed  by  the  junction  of  the  external  and  internal 
iliac  veins.  It  extends  from  the  sacro-iliac  articulation  to 
the  right  of  the  aortic  bifurcation,  where  they  unite  to  form 
the  vena  cava  inferior.  The  left  vein  is  behind  and  at  the 
inside  of  the  left  artery,  and  ends  behind  the  right  artery. 
The  right  vein  is  first  behind,  then  behind  and  at  the  out- 
side of  its  artery. 

Tributaries. — The  iliolumbar,  and  middle  sacral  veins. 

The  Vena  Cava  Inferior.      Fig.  106. 

Is  formed  at  the  right  of  the  abdominal  aorta,  and  behind 
the  right  iliac  artery  over  the  fifth  lumbar  vertebra,  by  the 
union  of  the  two  common  iliac  veins,  and  passes  upward 


THE  ABDOMEN,  INTERIOR.  521 

to  leave  the  abdominal  cavity  through  the  caval  opening  in 
the  diaphragm.  It  lies  at  the  right  side  of  the  aorta,  in 
contact  with  it  below,  but  separated  from  it  above  by  the 
right  crus  of  the  diaphragm  and  Spigelian  lobe  of  the  liver. 

The  vena  cava  is  crossed  by  the  right  spermatic  artery, 
transverse  colon,  mesentery,  duodenum,  pancreas,  portal 
vein,  and  liver,  and  lies  in  a  deep  groove  in  the  substance 
of  the  liver  (the  caval  fissure). 

Tributaries. — (i)  The  common  iliac  veins. 

(2)  The  lumbar,  four  on  each  side,  the  left  being  a  little 
longer  than  the  right. 

The  lumbar  veins  are  joined  together  by  a  vertical  vein 
which  runs  upward  in  front  of  the  transverse  processes  of 
the  vertebrae  to  communicate  above  with  the  azygos  major 
(on  the  right  side),  and  azygos  minor  (on  the  left  side). 
See  page  348. 

(3)  The  spermatic  veins  (ovarian  in  the  female).  Return 
the  blood  from  the  testicle  ;  on  the  cord  they  form  a  plexus 
of  dilated  and  convoluted  veins  called  the  pampitiifonn 
plexus.  In  the  female  this  plexus  is  formed  about  the 
ovar}'.  The  left  spermatic  (or  ovarian)  vein  empties  into 
the  left  renal  vein. 

(4)  The  renal  veins.      Return  the  blood  from  the  kidneys. 
The  left  is  a  little   longer  than  the   right,  and  receives 

the  left  spermatic  (or  ovarian)  vein.  The  renal  arter}'  lies 
behind  the  vein. 

(5)  The  suprarenal  veins.  These  return  the  blood  from 
the  bodies  of  the  same  name.  The  left  suprarenal  usually 
empties  into  the  left  renal,  the  right  into  the  vena  cava. 

(6)  The  hepatic  veins.  Two  or  three  large  veins.  Re- 
turn all  the  blood  from  the  liver  and  empty  into  the  vena 
cava  as  it  lies  in  the  caval  fissure  of  the  liver. 

(7)  The  inferior  phrenic  veins.      Collect  the  blood  from 


522  A  MANUAL   OF  ANATOMY. 

the  diaphragm,  and  accompany  the  arteries  of  the  same 
name.  The  left  usually  empties  into  the  left  suprarenal,  or 
renal. 

The  Kidneys.      Figs.  io6,  107. 

These  organs  are  situated  at  the  back  of  the  abdominal 
cavity,  on  either  side  of  the  spinal  column,  supported  by 
an  investment  of  adipose  and  connective  tissue.  The  long 
axis  of  the  kidney  is  vertical,  its  length  4  inches,  corres- 
ponding to  the  last  two  dorsal  and  first  two  lumbar  verte- 
brae, width  2^/^  inches,  and  thickness  i^  inches.  The 
right  is  usually  a  little  lower  than  the  left,  owing  to  the 
liver  above  it  crowding  it  downward. 

Relations. — Posteriorly,  the  kidney  rests  upon  the  dia- 
phragm in  front  of  the  eleventh  and  twelfth  ribs,  the  quad- 
ratus  lumborum,  and  psoas  muscles,  from  which  it  is  sepa- 
rated by  the  diaphragmatic  fascia  from  the  first,  the  anterior 
layer  of  the  lumbar  fascia  from  the  second,  and  by  the  ilio- 
psoas fascia  from  the  third.  Behind  it  pass  the  twelfth 
dorsal,  iliohypogastric,  and  ilio-inguinal  nerves. 

The  relations  of  the  pleura  are  important  though  not 
intimate.  Its  parietal  reflection  descends  into  the  angle 
between  the  diaphragm  and  the  thorax,  to  the  level  of  the 
lower  border  of  the  twelfth  dorsal  vertebra,  and  is  repre- 
sented by  a  line  crossing  the  neck  of  the  twelfth  rib  and  the 
outer  end  of  the  eleventh.  The  incisions  for  reaching  the 
kidney  may  open  into  the  pleural  cavity  if  carried  too  high. 

Anterior  surface  of  the  kidney.  The  right  is  crossed  in  its 
upper  half  by  the  liver,  in  the  lower  half  by  the  ascending 
colon  and  duodenum  (latter  covers  inner  one-fourth  of  lower 
half).  The  left  has  the  stomach  in  front  of  its  upper  third, 
the  splenic  artery  and  pancreas  in  front  of  the  middle  third, 
and  the  colon  in  front  of  the  lower  third. 


Fig.  106.  Dissection  of  Abdominal  Viscera  (Male).— a,  Right,  and  b,  Left 
kidney,  c,  Bladder,  d,  Inferior  vena  cava,  e,  Abdominal  aorta.  /,  Left,  and  g-, 
Right  suprarenal  bodies,  i,  i,  i,  Origin  of  diaphragm.  2,  Left  spermatic  vein  empty- 
ing into  renal  vein.    3,  Left  spermatic  artery.    4,  Right  spermatic  artery. 


524  A  MANUAL   OF  AXA  TOMY. 

On  the  outside,  the  right  hes  against  the  hver  for  its 
upper  three-fourths,  the  left  against  the  spleen  for  about  the 
same  extent.  Above,  the  suprarenal  bodies  rest  upon  the 
upper  and  inner  margin  of  the  kidneys.  On  the  inner  side 
are  the  arteries,  veins,  and  exit  of  the  ureters. 

The  arteries  are  derived  from  the  Aorta.  The  veins 
empty  into  the  V^ena  Cava.  The  ner\'es  are  derived  from 
the  solar  and  aortic  plexuses.  The  lymphatics  empty  into 
the  receptaculum  ch\-li. 

The  Suprarenal  Bodies.      Figs.   io6,  107. 

These  small  triangular  glands  are  found  resting  upon  the 
upper  and  inner  borders  of  the  kidneys.  Their  base  is 
about  one  and  three-fourths  inches,  their  height  about  one 
and  one-fourth  inches. 

The  right  suprarenal  body  is  behind  the  liver,  duodenum, 
and  in  contact  with  the  vena  cava,  the  left  behind  the 
stomach,  pancreas,  splenic  arter}',  and  has  the  spleen  to  the 
outer  side. 

The  arteries  are  from  the  Aorta,  Inferior  Phrenic,  and 
Renal.  The  veins  empty  into  the  vena  cava,  or  renal.  The 
nerves  are  derived  from  the  same  source  as  the  kidney. 
The  lymphatics  pass  to  the  renal  glands.  The  kidneys 
and  suprarenal  bodies  are  behind  the  peritoneum. 

The  Ureters.      Figs.  105  to  107,  112. 

Are  the  excretorv^  ducts  of  the  kidneys,  and  pass  down- 
ward to  empty  into  the  base  of  the  bladder.  They  are 
from  twelve  to  sixteen  inches  long,  and  below  the  kidney 
one-sixth  of  an  inch  in  diameter.  At  the  kidney  they 
become  expanded  to  form  the  sinus,  into  which  the  calices 
empty.  In  its  course  to  the  bladder  the  ureter  crosses  the 
psoas  muscle,  genitocrural  nerv^e,  common  iliac  arter}'  and 
vein.     It  lies  behind  the  peritoneum,  and  is  crossed  by  the 


THE  ABDOMEN,  INTERIOR.  525 

spermatic  vessels   (in   female,  ovarian),  and  at  the   bladder 
by  the  vas  deferens  (in  the  female  by  the  round  ligament). 

The  Ilio-Psoas  Fascia,      Fig.  103. 

Is  attached  to  the  crest  of  the  ilium,  the  outer  part  of 
Poupart's  ligament  blending  with  the  transversalis  fascia  ; 
when  the  femoral  vessels  are  reached  it  passes  behind  them 
to  form  the  posterior  layer  of  their  sheath  (as  the  transver- 
salis does  the  anterior  layer)  ;  it  is  then  attached  to  the  ilio- 
pectineal  line,  brim  of  the  true  pelvis,  to  the  bodies  and 
intervertebral  substances,  and  bases  of  the  transverse  pro- 
cesses of  the  lumbar  vertebrae,  as  well  as  to  the  tendinous 
arches  which  bridge  over  the  lumbar  arteries  ;  when  the 
diaphragm  is  reached  this  fascia  becomes  thickened  to  form 
the  lig-amentum  arcuatum  internum,  extending  from  the 
body  of  the  first  to  the  transverse  process  of  the  second 
lumbar  vertebra,  arching  over  the  psoas  muscle  ;  along  the 
outer  margin  of  the  psoas  the  fascia  is  attached  to  the  ante- 
rior lamella  of  the  lumbar  fascia. 

It  is  the  existence  of  this  fascia  that  determines  the  course 
of  purulent  collections  beneath  it  to  point  beneath  Poupart's 
ligament  at  the  outer  side  of  the  femoral  artery,  forming  a 
psoas  abscess.  Such  abscesses  are,  in  the  great  majority 
of  cases,  due  to  tubercular  disease  of  the  lumbar  vertebrae 
(Pott's  disease). 

The  anterior  layer  of  the  lumbar  fascia  is  seen  covering 
the  quadratus  lumborum  muscle.  Its  attachments  have 
already  been  given  (see  page  451).  Below,  it  becomes 
attached  to  the  crest  of  the  ilium  and  the  iliolumbar  liga- 
ment ;  above,  it  forms  the  lig-amentum  arcuatum  exter- 
num, q.  V.  (page  451). 

The  Femoral  Opening.      Figs.  103,  106. 

To  the  inner  side  of  the  external  iliac  vein,  just  under 


526  A  MANUAL  OF  ANATOMY. 

Poupart's  ligament,  is  seen  a  dimple  that  is  usually  occu- 
pied by  a  small  lymphatic  gland.  This  dimple  or  small 
fossa  is  due  to  a  slight  depression  in  the  transversalis  fascia, 
as  it  pouches  into  a  small  gap  that  is  left  between  the  vein 
and  Gimbernat's  ligament.  The  gap  (as  seen  after  dissec- 
tion or  after  being  made  by  a  hernia)  is  the  femoral  ring, 
and  the  transversalis  fascia  that  covers  it  over  is  the  septum 
crurale.  A  femoral  hernia  bulges  the  septum  crurale  before 
it  in  its  descent  to  leave  the  abdominal  cavity  by  the  fem- 
oral opening.  As  the  dissection  progresses  the  femoral 
opening  will  be  seen  to  have  these  boundaries  :  To  the  in- 
side, Gimbernat's  ligament,  conjoined  tendon,  and  triangu- 
lar ligament  ;  in  front,  Poupart's  ligament ;  to  the  outside, 
the  external  iliac  vein  covered  by  the  sheath  (formed  by 
the  union  of  the  iliac  fascia  beneath,  with  the  transversalis 
fascia  above)  ;  behind,  the  pubic  portion  of  the  fascia  lata 
covering  the  pectineus  muscle  and  the  horizontal  ramus  of 
the  pubic  bone. 

The  description  of  the  canal  will  be  given  later. 

DISSECTION. 

Ligate  the  vena  cava  at  its  beginning,  divide  and  remove  it,  with  all  the 
veins  emptying  into  it. 

Carefully  remove  the  iliopsoas  and  anterior  layer  of  the  lumbar  fasciae. 
Dissect  out  the  receptaculum  chyli,  splanchnic  nerves,  sympathetic  cord  and 
ganglia,  the  beginning  of  the  lumbar  arteries,  the  branches  of  the  lumbar  plexus 
external  to  the  psoas  muscle,  the  psoas  and  iliacus  muscles.  Follow  the  vas 
deferens  to  the  bladder,  or  the  round  ligament  to  the  uterus. 

Trace  the  ureters  to  the  bladder. 

The  Lumbar  Sympathetic  Ganglia  and  Cord.    Figs.  74, 
106,  107,  113. 
Consist  of  four  ganglia  connected  together  by  the  sym- 
pathetic  cord,  which  above  comes   from  the   thorax,    and 
below  passes  to  the  sacral  ganglia.     These  ganglia  lie  in 


THE  ABDOMEN,  INTERIOR.  527 

front  of  the  vertebrae,  the  right  behind  the  vena  cava,  the 
left  behind  the  outer  border  of  the  aorta,  both  close  to  the 
anterior  border  of  the  psoas  muscle.  The  cord  passing  to 
the  sacral  ganglia  goes  behind  the  iliac  vessels,  internal  to 
the  psoas  muscle. 

The  Receptaculum  Chyli. 

This  is  the  dilated  pouch  from  which  the  thoracic  duct 
arises.  It  receives  the  lymph  and  chyle  from  the  abdomi- 
nal walls  and  organs.     See  page  344. 

It  lies  to  the  right  and  behind  the  abdominal  aorta,  be- 
tween it  and  the  right  crus  of  the  diaphragm,  and  upon  the 
body  of  the  second  lumbar  vertebrae.  It  is  one  and  one- 
half  inches  long  and  one-quarter  of  an  inch  in  diameter. 

Psoas  Mag-nus.     Figs.  103,  107. 

Origin. — By  five  muscular  slips  from  the  anterior  surfaces 
and  lower  borders  of  the  transverse  processes  of  the  lumbar 
vertebrae,  from  the  sides  and  intervertebral  discs  of  the  last 
dorsal  and  lumbar  vertebrae.  Over  the  centre  of  the  bodies 
of  the  vertebrae  small  gaps  are  left  in  the  muscular  attach- 
ment for  the  passage  of  the  lumbar  vessels  and  lumbar 
branches  of  the  sympathetic  nerves. 

Insertion. — By  a  strong  tendon  into  the  lesser  trochanter 
of  the  femur. 

Nerve  Supply. — Muscular  branches  from  the  anterior 
division  of  the  second  and  third  lumbar  nerves. 

Action. — For  action  on  femur  see  under  Iliacus.  On  the 
spine  it  flexes  the  last  dorsal  and  lumbar  vertebrae  upon 
the  pelvis. 

Iliacus.     Figs.  103,  107. 

Origin. — From  the  base  of  the  sacrum,  the  sacro-iliac 
and  iliolumbar  ligaments,  the  iliac    fossa,  the  iliac  crest, 


528  A  MANUAL  OF  ANATOMY. 

Spinous  processes  and  bone  between  them,  from  the  capsule 
of  the  hip  joint. 

Insertion. — Into  the  outer  border  of  the  tendon  of  the 
psoas,  also  into  an  inch  of  the  line  from  the  lesser  tro- 
chanter to  the  linea  aspera. 

Nerve  Supply. — By  branches  from  the  anterior  crural, 
derived  from  the  second  and  third  lumbar  nerves. 

Actions. — The  psoas  magnus  and  iliacus  act  as  one  mus- 
cle upon  the  femur.  They  are  the  direct  and  most  power- 
ful flexors  of  the  thigh,  upon  the  abdomen,  or  the  reverse. 
From  the  insertion  of  their  tendon  into  the  lesser  trochanter, 
this  insertion  being  outside  of  the  centre  of  motion  of  the 
head  of  the  femur  in  the  acetabulum.  It  follows  that 
flexion  being  arrested,  the  great  trochanter  will  be  raised 
(carried  forward)  and  internal  rotation  will  result. 

Psoas  Parvus.     Fig.  107. 

When  present  this  muscle  will  be  found  arising  from  the 
intervertebral  disc  between  the  bodies  of  the  last  dorsal  and 
first  lumbar  vertebrae,  and  from  the  adjacent  portions  of 
those  vertebrae. 

Insertion. — Into  the  iliopectineal  line. 

Nerve  Supply — From  the  first  lumbar  nerve. 

Action. — To  flex  the  pelvis  on  the  spine  or  the  reverse. 

Quadratus  Lumboruni.     Figs.  106,  107. 

Origin. — From  the  iliolumbar  ligament,  from  the  inner 
lip  of  the  crest  of  the  ilium  for  two  inches  posterior  to  the 
iliolumbar  ligament,  from  the  tips  of  the  transverse  pro- 
cesses of  the  three  lower  lumbar  vertebrae. 

Insertion.— \vA.o  the  inner  half  of  the  lower  border  of  the 
last  rib,  and  the  transverse  processes  of  the  three  upper 
lumbar  vertebrae. 


THE  AB DOMEX,  INTERIOR.  529 

Na-i'c  Supply. — Filaments  from  the  last  dorsal  and  upper 
lumbar  ner\'es. 

Action. — A  lateral  flexor  of  the  spine.  By  fixing  the 
last  rib  it  gives  the  diaphragm  a  firm  point  for  contraction 
and  so  aids  inspiration. 

DISSECTION. 

Trace  the  brandies  of  the  lumbar  nerves  through  the  psoas  muscle. 

The  Last  Dorsal  Nerve.      Figs.  105,  106,  107. 

Courses  outward  and  downward  just  below  the  lower 
border  of  the  last  rib,  crossing  the  quadratus  lumborum,  to 
disappear  through  the  lumbar  fascia,  and  enter  between 
the  transversalis  and  internal  oblique  muscles,  where  it 
divides  into  two  branches. 

The  anterior  branch  continues  to  the  rectus  and  pyra- 
midalis  muscles,  the  lateral  or  iliac  pierces  the  internal  and 
external  oblique  muscles  about  three  inches  above  the  crest 
of  the  ilium  and  turns  downward  to  supply  the  integument 
over  the  crest  of  the  iHum  in  front  of  and  as  low  down  as 
the  great  trochanter. 

The  Lumbar  Plexus,      Figs.  103  to  107. 

The  lumbar  plexus  is  formed  by  the  anterior  divisions  of 
the  first  four  lumbar  nerves  and  a  branch  from  the  last 
dorsal. 

From  the  fourth  lumbar  nerve  a  branch  descends  to  join 
the  fifth  (anterior)  division,  and  the  trunk  thus  formed 
passes  to  the  upper  margin  of  the  sacral  plexus  as  the 
lumbosacral  cord. 

The  lumbosacral  cord   lies  between  the  inner  border  of 
the  psoas  muscle  and   the  base  of  the  sacrum,  and  behind 
the  iliac  vessels.      The   lumbar  nerves  are  connected  to  the 
sympathetic  ganglia  by  slender  filaments. 
34 


530  A  MANUAL  OF  ANATOMY. 

The  Branches  of  the  lumbar  plexus  are  as  follows  : — 
The  first  nerve  having  received  the  branch  from  the  last 
dorsal,  divides  into  the  iliohypogastric  and  ilio-inguinal. 
From  the  first  and  second  is  formed  the  genitocrural. 
From  the  second  and  third,  the  external  cutaneous.  From 
the  second,  third,  and  fourth,  the  anterior  crural  and  obtu- 
rator. From  the  third  and  fourth,  the  accessory  obturator. 
And  from  the  fourth  the  branch  passes  to  enter  into  the 
lumbosacral  cord. 

All  these  branches  are  formed  within  the  substance  of  the 
psoas  magnus  muscle. 

The  Nerves. 

(i)  The  iliohypog-astric  branch.  From  the  first  lumbar. 
Issues  from  the  upper  border  of  the  psoas,  crosses  the 
quadratus  lumborum  and  iliacus  obliquely  to  enter  the 
transversalis  muscle  over  the  middle  of  the  crest  of  the 
ilium.  It  divides  into  two  branches  ;  tlie  iliac,  which 
pierces  the  abdominal  muscles  and  supplies  the  integument 
over  the  outer  and  posterior  surface  of  the  crest  as  far  as  the 
great  trochanter,  being  posterior  to  the  iliac  branch  of  the 
last  dorsal  nerve. 

The  hypogastric  branch,  which  passes  through  the  in- 
ternal oblique  about  one  inch  in  front  of  the  anterior  supe- 
rior iliac  spine,  extends  downward  and  forward  to  appear 
through  the  external  oblique  about  two  inches  above  the 
spine  of  the  pubes,  supplying  the  integument  in  front  of  the 
pubes  and  dorsum  of  the  penis. 

(2)  The  ilio-ing-uinal.  From  the  first  lumbar.  It 
is  found  at  the  outer  border  of  the  psoas  just  below  the 
iliohypogastric,  takes  a  course  parallel  with  it  but  a 
little  lower,  to  follow  close  to  the  crest  of  the  ilium  and 
Poupart's     ligament,    and    appear    through    the    external 


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532  A  MANUAL   OF  ANATOMY. 

abdominal  ring  behind  the  cord  (or  round  ligament),  to  be 
distributed  to  the  integument  over  the  upper  and  inner  part 
of  the  thigh  and  outer  surface  of  the  scrotum  or  labium 
majus. 

(3)  The  genitocrural,  from  the  first  and  second  lumbar 
nerves. 

This  nerve  appears  at  the  inner  side  of  the  psoas,  runs 
downward  upon  its  anterior  surface,  and  divides  just  above 
Poupart's  ligament  into  the  genital  and  crural  branches. 
The  genital  branch  turns  outward  to  join  the  cord  and 
leave  the  abdomen  through  the  internal  abdominal  ring  to 
supply  the  cremaster  muscle  (in  the  female  the  round  liga- 
ment). The  crnral  branch  continues  downward  under 
Poupart's  ligament  at  the  outer  side  of  and  in  front  of  the  ex- 
ternal iliac  and  femoral  arteries,  pierces  the  fascia  lata  at  the 
lower  border  of  the  saphenous  opening  (two  inches  below 
Poupart's  ligament),  and  supplies  the  central  and  upper 
region  of  the  front  of  the  thigh. 

(4)  The  external  cutaneous.  From  the  second  and  third 
nerves.  Emerges  from  the  outer  border  of  the  psoas  mus- 
cle, below  the  crest  of  the  ilium,  extends  outward  and 
downward  across  theiliacus  muscle,  passes  under  Poupart's 
ligament  close  to  the  anterior  superior  iliac  spine,  in  front 
of  the  origin  of  the  sartorius,  descends  vertically  in  a  canal 
in  the  fascia  lata  for  four  or  five  inches,  then  becomes 
superficial  and  supplies  the  integument  over  the  anterior 
and  outer  surfaces  of  the  thigh,  nearly  to  the  knee.  Just 
after  coming  out  from  under  Poupart's  ligament,  a  branch 
is  given  off  that  turns  backward  to  supply  the  skin  over  the 
great  trochanter. 

(5)  The  anterior  crural  nerve.  Formed  from  the  second, 
third,  and  fourth  lumbar  nerves.  Descends  in  the  interval 
between  the   psoas  and  iliacus  muscles,  being   covered  by 


Fig.  io8.  The  Mutual  Relations  of  the  Thoracic  and  Abdominal  Vis- 
cera. [Figs.  io8  and  109  were  made  after  long  transfixion  pins  had  been  passed 
through  the  lower  border  of  the  thorax  and  driven  firmly  into  the  plank  upon  which 
the  subject  rested.  These  pins  were  inserted  previous  to  any  dissection  and  the  pho- 
tographs were  taken  with  the  subject  horizontal.]— a,  Heart  in  its  natural  position,  b. 
Stomach,  c.  Left  lobe  of  liver,  d.  Right  lobe  of  liver,  e,  Diaphragm  covering  liver. 
f.  Left  and  ^,  Right  lung,     h,  The  great  omentum  covering  the  intestines. 


534  A  MANUAL   OF  ANATOMY. 

the  former  ;  under  Poupart's  ligament  it  lies  external  to  the 
femoral  artery ;  a  little  lower  it  breaks  up  into  its  branches, 
muscular  and  cutaneous.     See  Thigh,  anterior. 

The  muscular  bratiches  supply  the  pectineus  (by  a  branch 
which  passes  behind  the  femoral  vessel),  sartorius,  rectus 
femoris,  vasti,  and  crureus.  The  hip  joint  receives  a  small 
branch  from  the  nerve  to  the  rectus,  and  the  knee,  from  the 
nerves  to  the  vasti  and  crureus. 

The  cutaneous  branches.  The  middle  pierces  the  fascia 
lata  three  or  four  inches  below  Poupart's  ligament  and  sup- 
plies the  anterior  region  to  the  knee.  The  internal  is  dis- 
tributed to  the  antero-internal  lower  two-thirds  of  the  thigh 
and  knee. 

The  long  or  internal  saphenous  nerve.  Follows  the 
femoral  artery  through  Hunter's  canal  until  the  artery  turns 
backward  through  the  opening  in  the  adductor  magnus. 
In  this  canal  the  nerve  Hes  first  to  the  outside  of  the  artery, 
then  crosses  it  in  front  to  reach  the  inside. 

From  Hunter's  canal,  the  nerve  continues  downward, 
passes  between  the  sartorius  and  gracilis  (behind  the  former 
as  usually  given),  and  appears  superficial  at  the  inner  side 
of  the  knee,  and  supplies  the  antero-internal  surfaces  of 
knee,  leg,  and  ankle.  In  its  course  from  Hunter's  canal  to 
the  knee  the  nerve  is  accompanied  by  the  superficial  branch 
of  the  anastomotica  magna  artery.  In  the  leg,  the  nerve 
follows  the  internal  saphenous  vein.  Just  above  the  knee 
the  nerve  gives  off  the  branch  which  supplies  the  antero- 
internal  surface  of  that  joint. 

(6)  The  obturator  nerve.  From  the  second,  third,  and 
fourth  lumbar  nerves.  Descends  between  the  psoas  and  base 
of  the  sacrum,  behind  the  iliac  vessels,  passes  forward  and 
inward  just  below  the  level  of  the  brim  of  the  pelvis  and 
between  the  peritoneum  and  pelvic  fascia,  to  leave  the  pelvis 


Fig.  109.  Mutual  Relations  of  Thoracic  and  Abdominal  Viscera.  [The 
ribs  have  been  entirely  removed.  Subject  horizontal.]— a,  Heart  turned  more  to  the 
left  than  normal,  owing  to  the  left  lung  having  been  removed.  *,  Stomach.  Its  fun- 
dus pushes  upward  behind  apex  of  heart,  c  and  d.  Left  and  right  lobes  of  the  liver. 
e  and  /,  Right  and  left  halves  of  the  diaphragm.  The  close  anatomical  (as  well  as 
clinical)  relations  between  the  heart,  lungs,  liver,  and  stomach  are  shown  in  this  and 
the  preceding  Figure. 


536  A  MANUAL   OF  ANATOMY. 

by  the  gap  in  the  upper  margin  of  the  obturator  membrane. 
It  is  accompanied  in  its  course  by  the  artery  of  the  same 
name  if  it  is  a  branch  from  the  internal  iliac.  In  the  thigh 
the  nerve  issues  from  the  obturator  canal  above  or  through 
the  upper  part  of  the  obturator  externus  muscle,  where  it 
divides  into  two  branches.  Tlie  anterior  branch  descends 
between  the  pectineus  and  adductor  longus  in  front  and 
the  adductor  brevis  behind,  supplying  these  muscles  and 
terminating  in  the  gracilis.  It  also  sends  a  cutaneous 
branch  to  the  lower  and  inner  third  of  thigh.  The  posterior 
branch  goes  behind  the  adductor  brevis  and  suppHes  the 
adductor  magnus,  continues  downward,  pierces  the  adduc- 
tor magnus  just  above  the  femoral  opening,  joins  the  pop- 
liteal vessels,  and  ends  in  the  posterior  part  of  the  knee- 
joint. 

The  obturator  externus  receives  its  nerve  supply  from 
the  posterior  division  of  the  nerve.  A  filament  is  also  sent 
to  the  hip-joint. 

(7)  The  obturator  accessory.  When  present  arises  from 
the  third  and  fourth  lumbar  nerves.  Descends  between 
the  psoas  and  internal  iliac  artery  (behind  both)  over  the 
anterior  border  of  the  pubes  to  the  pectineus,  which  it  sup- 
plies, then  communicates  with  the  obturator  nerve  and  con- 
tinues to  the  hip-joint. 

DISSECTION. 

Inflate  the  bladder.  Dissect  the  peritoneum  from  it  and  the  rectum.  Clean 
the  internal  iliac  vessels  and  their  branches,  also  the  sacral  plexus.  In  doing 
this  notice  the  pelvic  fascia,  the  so-called  "  white  line,"  and  the  rectovesical 
fascia. 

To  dissect  the  pelvic  cavity  and  viscera  requires  that  the  lateral  vs^all  shall 
be  removed  from  one  side  as  represented  in  the  plates ;  as  this  destroys  the  side 
removed  for  dissection  of  the  gluteal  region,  it  is  not  practicable,  and  the  dis- 
sector must  do  the  best  possible  with  the  pelvis  intact. 

Trace  the  ureters,  vasa  deferentia,  and  expose  the  seminal  vesicles.     In 


THE  ABDOMEN,  INTERIOR.  537 

the  female  carefully  note  the  relations,  position  of  bladder,  uterus,  uterine  lig- 
aments, ovaries,  tubes,  and  rectum.  Trace  the  round  ligaments,  ureters, 
ovarian  and  uterine  arteries.  See  the  Dissection  of  Perineum,  page  397 
male,  and  422  female. 

The  Bladder.      Figs.  84,  95,  103  to  113, 

The  bladder  is  situated  in  the  pelvic  cavity.  In  the  living, 
when  empty  it  is  probably  round  ;  when  distended,  oval. 
When  empty  it  lies  entirely  behind  the  symphysis  ;  if  mod- 
erately distended,  reaches  to  the  top  ;  if  fully  distended, 
may  reach  two  inches  above  the  symphysis,  and  in  patho- 
logical distention  may  extend  to  or  even  above  the  umbili- 
cus. When  distended  the  long  axis  of  the  bladder  is  paral- 
lel with  a  line  connecting  the  umbilicus  and  the  anus. 

Peritoneal  Covering-. — From  the  anterior  abdominal 
Avail  the  peritoneum  extends  on  to  the  top,  sides,  and  down 
the  back  of  the  bladder  to  within  an  inch  or  an  inch  and 
a  half  of  the  prostate,  where  it  is  reflected  on  to  the  rectum, 
forming  the  rectovesical  pouch  in  the  male  ;  (in  the  female 
the  peritoneum  extends  backward  on  to  the  uterus,  and  the 
fossa  is  called  the  uterovesical). 

The  reflections  of  the  peritoneum  from  the  bladder  to  the 
adjacent  walls  of  the  abdomen  or  viscera  are  termed  "  false  " 
ligaments,  and  they  are  well  named  on  account  of  the  false 
impression  that  they  convey  of  their  function  and  appear- 
ance. The  student  needs  simply  to  remember  that  the  blad- 
der is  underneath  the  pelvic  peritoneum  and  raises  it  upward 
as  it  fills  (the  loose  covering  of  peritoneum  allowing  this 
action,  and  steadying  the  bladder  when  full). 

Retzius'  space  is  the  interval  between  the  anterior  wall  of 
the  bladder  and  the  inner  surface  of  the  symphysis  pubes, 
and  lower  abdominal  wall.  The  extent  of  space  varies  with 
the  distention  of  the  bladder.  When  the  bladder  is  empty 
the  space  is  obliterated  ;  when  the  bladder  is  very  full  the 


538  A  MANUAL  OF  ANATOMY. 

space  may  extend  two  inches  above  the  top  of  the  symphy- 
sis. As  the  bladder  rises  it  takes  with  it  the  peritoneum  ; 
consequently,  the  viscus  can  be  opened  in  this  condition 
without  entering  the  peritoneal  cavity.  The  extent  of  space 
is  further  increased  by  inflating  the  rectum,  thus  crowding 
the  bladder  upward  and  forward.  This  manoeuvre  is  util- 
ized in  suprapubic  cystotomies. 

The  True  Ligaments  of  the  Bladder. 

{a)  The  urachus.  This  is  the  fibrous  cord  that  extends 
from  the  top  of  the  bladder  to  the  umbilicus,  and  represents 
the  canal  which  connected  the  bladder  with  the  allantois  in 
the  fcetus.  See  Fig.  95.  {f)  and  {c)  The  obliterated 
hypogastric  arteries.  These  fibrous  cords  extend  from  the 
sides  of  the  bladder,  where  they  are  continuous  with  the 
superior  vesical  arteries,  to  the  umbilicus.  In  the  fcetus 
they  were  pervious  and  carried  the  foetal  blood  to  the 
mother,  {d)  The  rectovesical  fascia.  Parts  of  this  sheet 
of  fascia  are  designated  as  the  anterior  and  lateral  true  liga- 
ments of  the  bladder  and  the  ligament  of  the  rectum.  See 
page  399. 

Relations  of  the  Bladder  (when  moderately  distended). 
— Anteriorly,  the  inner  surface  of  the  pubic  bones  and 
anterior  portions  of  the  obturator  internus  muscles.  Later- 
ally, ureters,  obliterated  hypogastric  arteries,  vas  deferens 
(in  the  male,  round  ligament  in  the  female),  anterior 
branches  of  the  internal  iliac  artery,  levator  ani  and  obtura- 
tor internus  muscles.  Posteriorly ;  the  upper,  peritoneal 
surface,  with  the  omega  loop  ;  the  lower,  nonperitoneal, 
with  the  rectum,  seminal  vesicles,  terminations  of  ureters, 
and  vasa  deferentia.  In  the  female  the  posterior  surface  is 
in  relation  to  the  uterus  and  upper  part  of  the  vagina. 

Superiorly,  the  small  intestines  and  omega  loop.     Infe- 


0  9 

Fig.  no.  Female  Pelvic  Viscera. — i,  Aorta  at  bifurcation.  2,  Inferior  me- 
senteric artery.  3,  Rectum.  4,  4,  Fallopian  tube.  5,  5,  Ovaries.  6,  6,  Round  liga- 
ments. 7,  Fimbriated  extremity  of  Fallopian  tube.  8,  Uterus.  9,  Bladder  moder- 
ately distended.  10,  Uterovesical  pouch.  4,  5,  6,  Are  enclosed  within  a  fold  of  peri- 
toneum which  constitutes  the  broad  ligament  of  the  uterus. 


F!g.  III.  Female  Pelvic  \'iscera.  (Bladder  empty.) — i,  Douglas'  pouch. 
2,  Rectum.  3,  Recto-uterine  ligament.  4,  Ovary.  5,  Ovarian  (utero-ovarian)  liga- 
ment.   6,  Round  ligament.     7,  Fallopian  tube.     Its  fimbriated  extremity  is  very  plain. 


540  A  MANUAL   OF  ANA  TOMY. 

riorly,  prostate,  seminal  vessels,  urethra,  rectovesical  fascia, 
venous  plexuses. 

The  External  Trig-one.  Fig.  84.  This  is  a  triangular  sur- 
face on  the  posterior  wall  of  the  bladder  bounded  at  the  apex 
by  the  prostate,  on  the  sides  by  the  diverging  seminal  vesi- 
cles and  the  vas  deferens,  and  above  by  the  reflection  of  the 
peritoneum  from  the  posterior  wall  of  the  bladder  to  the 
front  of  the  rectum.  This  fold  is  from  one  to  one  and  one- 
half  inches  from  the  prostate  and  three  and  one-half  inches 
from  the  anus. 

This  surface  of  the  bladder  is  in  close  relation  to  the 
rectum  and  only  separated  from  it  by  some  rectovesical 
fascia.  Through  this  space  a  trocar  might  be  introduced 
from  the  rectum  into  the  bladder,  though  it  is  not  practiced 
now. 

The  Ureter.     Figs.  103  to  107,  112. 

This  is  a  small  canal  (one-sixteenth  of  an  inch  in  diameter), 
which  extends  from  the  kidney  to  the  bladder,  carrying  the 
urine  from  the  former  to  the  latter.  Its  average  length  is 
twelve  to  sixteen  inches.  It  lies  behind  the  peritoneum  and 
is  enclosed  in  the  extraperitoneal  tissue. 

After  crossing  the  psoas  muscle  and  the  iliac  vessels  it 
passes  to  the  lateroposterior  wall  of  the  bladder,  curves  down- 
ward and  inward  to  enter  the  substance  of  the  bladder  in 
front  of  the  upper  end  of  the  seminal  vessels  ;  after  travers- 
ing the  bladder  wall  they  open  upon  its  inner  surface  about 
three-fourths  of  an  inch  apart  and  the  same  distance  pos- 
terior to  the  internal  opening  of  the  urethra.  In  the  male 
the  vas  deferens  passes  between  the  ureter  and  bladder.  In 
the  female,  the  ureter  runs  in  front  of  the  cervix  uteri  and 
upper  part  of  the  vagina  (between  these  and  the  bladder). 
At  the  base  of  the  bladder,  where  the  ureters  are  entering 


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542  A  MANUAL  OF  ANA  TOMY. 

its  wall,  they  lie  one  and  one-half  inches  posterior  to  the 
prostate  and  two  inches  apart.  Their  course  through  the 
bladder  wall  is  very  oblique,  so  that  they  issue  only  three- 
fourths  of  an  inch  posterior  to  the  internal  opening  of  the 
urethra  and  the  same  distance  apart. 

The  Vas  Deferens.   Figs.  92,  94,  103,  112,  84. 

One  on  each  side.  Conveys  the  seminal  fluid  from  the 
testicle  to  the  seminal  vesicles.  It  is  about  twenty-four 
inches  long  and  one-sixteenth  of  an  inch  in  diameter. 

Starting  from  the  globus  minor  of  the  testicle,  it  ascends 
with  the  structures  forming  the  cord  through  the  external 
abdominal  ring,  the  inguinal  canal,  the  internal  ring,  around 
the  deep  epigastric  artery.  It  now  leaves  the  other  structures 
of  the  cord  and  runs  inward  across  the  psoas  muscle  and 
external  iliac  vessels  to  the  side  of  the  bladder.  In  the  ab- 
domen it  lies  behind  the  peritoneum  for  its  entire  course  to 
the  bladder.  Descending  along  the  posterior  wall  of  the 
bladder,  it  passes  in  front  of  the  obliterated  hypogastric 
arteries  and  the  ureter  (between  them  and  the  bladder)  to 
the  notch  at  the  base  of  the  prostate.  In  the  last  part  of  its 
course  it  is  between  the  bladder  and  the  rectum.  In  the 
prostatic  notch  the  vas  unites  with  the  seminal  vesicle  to 
form  a  single  tube,  the  ejaculatory  duct,  which  continues 
through  the  prostate  to  open  upon  the  floor  of  the  urethra. 
The  length  of  the  duct  is  about  three-fourths  of  an  inch. 

The  one  and  one-half  inch  of  the  vas  adjacent  to  the 
prostate  is  dilated  and  receives  the  name  of  ampulla.  See 
page  420. 

The  Uterus.     Figs,  no,  in. 

The  uterus  is  the  reproductive  organ  of  the  female.  It 
varies  in  size  with  the  age  and  condition  of  the  individual.    In 


THE  ABDOMEN,  INTERIOR.  543 

the  normal  adult  it  measures  about  three  inches  in  length,  two 
inches  in  width  at  the  upper  part  and  one  at  the  lower,  and 
one  inch  in  thickness.  It  is  placed,  with  its  widest  dimen- 
sion transverse,  between  the  bladder  and  rectum  and  at  the 
upper  end  of  the  vagina,  into  which  it  projects.  The  organ 
is  divided  into  the  body,  the  upper  portion  ;  the  ist/uims,  the 
middle  narrow  portion  ;  and  the  cervix,  the  lower  portion. 
The  cervix  is  about  an  inch  long  ;  the  upper  part  outside  of 
the  vagina  is  the  extravaginal  part,  the  lower  half-inch 
within  the  vagina,  intravaginal.  The  intravaginal  portion 
of  the  cervix  presents  the  opening  of  the  cavity  of  the  uterus, 
or  the  OS  uteri. 

Peritoneal  Reflections. — The  peritoneum  is  reflected  from 
the  bladder  over  the  uterus  to  the  rectum.  It  covers  the 
body  of  the  uterus  in  front,  and  behind  descends  on  to  the 
vagina  about  an  inch  before  it  is  reflected  on  to  the  rectum. 
The  anterior  depression  between  the  bladder  and  the  uterus 
is  the  uterovesical  fossa  ;  the  posterior,  between  the  rectum 
and  the  vagina  and  uterus,  is  the  recto-vaginal,  or  the  pouch 
of  Douglas. 

TJie  Ligaments  of  the  Uterus. — The  peritoneum  forms 
semilunar  folds  between  the  sides  of  the  uterus  and  the 
bladder  in  front  and  the  rectum  behind  ;  these  are  the  an- 
terior and  posterior  ligaments  of  the  organ.  These  folds 
constitute  the  lateral  boundaries  of  the  anterior  and  posterior, 
or  uterovesical  and  rectovaginal  pouches. 

From  the  sides  of  the  uterus  the  peritoneum  extends  in 
a  broad  double  fold  to  the  lateral  pelvic  wall,  forming  the 
broad  lig-aments  of  the  uterus. 

In  the  free  margin  of  each  ligament  is  the  Fallopian 
tube  ;  on  the  posterior  surface,  the  ovary  connected  to  the 
uterus  by  a  band  about  one  and  one-half  inches  long 
(the   ligament  of  the  ovary) ;  at  about  the  middle  of  the 


544  A  MANUAL   OF  ANA  TOMY. 

broad  ligament  is  the  ovarian  artery  and  round  ligament ; 
at  its  base  the  ureter,  uterine  artery,  veins,  and  nerves. 

The  Round  Ligament,     Figs,  i  lO,   ill. 

Is  a  fibromuscular  flattened  cord  about  five  inches  long,, 
extending  from  the  upper  angle  of  the  uterus  outward  and 
forward  behind  the  peritoneum,  to  cross  the  iUac  vessels, 
curve  around  the  deep  epigastric  artery,  and  leave  the  abdo- 
men by  the  internal  abdominal  ring.  After  passing  through 
the  inguinal  canal  the  round  ligament  issues  from  the  ex- 
ternal ring  and  becomes  lost  in  the  tissues  in  front  of  the 
pubes.  It  carries  with  itself  into  the  inguinal  canal  a  tubu- 
lar process  of  peritoneum,  called  the  canal  of  Nuck  ;  this 
sometimes  persists  into  adult  life  and  forms  a  sac  for  an 
inguinal  hernia.  The  cord  receives  blood  from  the  ovarian, 
superior  vesical,  and  deep  epigastric  arteries. 

The  Fallopian  Tubes.    Figs,  no,  in. 

One  on  each  side,  about  five  inches  long,  extend  out- 
ward from  the  superior  angle  of  the  uterus  in  the  free 
border  of  the  broad  ligament.  Near  the  uterus  they  are 
very  small,  gradually  enlarge  as  they  pass  outward,  finally 
terminate  in  a  tasseled,  or  fimbriated  extremity.  It  is 
attached  by  one  of  these  fimbriae  to  the  ovary.  The  open- 
ing of  the  tube  into  the  peritoneum  is  the  only  communica- 
tion that  the  peritoneal  sac  has  with  the  exterior  of  the 
body. 

The  Ovary.      Figs,  no,  iii. 

The  ovary  is  a  small  body  one  and  one-half  by  three- 
fourths  by  half  an  inch,  oval  in  outline,  its  long  axis  nearly- 
vertical,  situated  upon  the  posterior  surface  of  the  broad  liga- 
ment of  the  uterus,  and  connected  to  the  uterus  by  a  band 
one  and  one-half  inches  long  that   is  called  the  lig-ament 


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546  A  MANUAL  OF  ANATOMY. 

of  the   ovary,   and  to  the  Fallopian  tube  by  one  of  the 
fimbriae. 

The  Veins  form  a  Plexus  about  the  ovary  and  in  the 
meshes  of  the  broad  ligament  (the  pampiniform  plexus). 
The  right  ovarian  vein  opens  into  the  vena  cava,  the  left 
into  the  left  renal  vein. 

The  Lymphatics. — The  distribution  of  the  lymph  drained 
from  the  female  genitals  is  important  as  giving  a  clue  to  the 
site  of  a  possible  infection.  The  vulvar  lymphatics  empty 
into  the  inguinal  glands.  Inflammation  of  the  vulva  may 
cause  an  enlargement  of  the  inguinal  glands  constituting,  as 
in  the  male,  a  bubo. 

The  vaginal  and  uterine  lymphatics  pass  to  the  pelvic 
glands,  from  the  round  ligament  to  the  inguinal  glands,  and 
from  the  broad  ligament  to  the  lumbar  glands. 

The  Nerves  are  derived  from  the  third  and  fourth  lum- 
bar, hypogastric,  and  renal  sympathetic  plexuses. 

The  Internal  Iliac  Artery  and.  its  Branches.      Figs.  112, 

113,   114- 

The  internal  iliac  is  the  posterior  branch  of  the  common 
iliac,  as  the  external  is  the  anterior  branch.  The  terms  ex- 
ternal and  internal  as  applied  to  these  arteries  are  misno- 
mers, for  both  arteries  are  internal,  within  the  abdominal 
cavity,  the  proper  designation  would  be  as  indicated,  anterior 
and  posterior. 

The  internal  iliac  descends  along  the  pelvic  wall  to  the 
upper  margin  of  the  great  sacrosciatic  foramen,  where  it 
divides  into  the  anterior  and  posterior  trunk. 

The  anterior  trunk  gives  off  the  vesical,  hemorrhoidal, 
uterine,  vaginal,  obturator,  sciatic,  and  pudic  branches. 

(a)  The  vesical  are  three  in  number,  the  superior,  middle, 


THE  ABDOMEN,  INTERIOR.  547 

and  inferior,  which  are  distributed  to  the  bladder.  The 
superior  gives  off  the  deferential  artery  to  the  vas  deferens 
(in  the  female  a  similar  one  to  the  round  ligament),  and  at 
the  bladder  the  obliterated  hypogastric,  which  in  the  fcetus 
was  pervious.  (Ji)  The  middle  hemorrhoidal.  This  sup- 
plies the  middle  section  of  the  rectum,  anastomosing  above 
with  the  superior  hemorrhoidal  from  the  inferior  mesenteric 
and  below  with  the  inferior  hemorrhoidal  from  the  internal 
pudic.  (r)  Uterine.  Supplies  the  lower  section  of  the 
uterus  ;  the  two  arteries  form  an  anastomosis  around  the 
neck  of  the  cervix  by  the  circular  artery,  [d)  The  vaginal. 
Four  or  five  small  arteries  to  the  side  of  the  vagina,  (e) 
The  obturator.  It  runs  forward  just  below  the  nerve  which 
it  accompanies  through  the  obturator  canal.  For  the  ter- 
minal distribution,  see  page  583.  The  pelvic  branches  are 
small,  only  one  of  them  being  of  any  size,  viz.  :  the  pubic, 
which  anastomoses  upon  the  inner  surface  of  the  pubes  with 
the  pubic  branch  of  the  deep  epigastric.  Frequently  this 
anastomosis  is  by  larger  trunks,  or  the  obturator  may  rise 
(one  in  three  and  a  half  cases)  from  the  deep  epigastric 
artery  and  pass  to  the  obturator  canal  at  the  outer  side  of 
the  femoral  opening,  or  in  a  few  cases  (one  in  ten)  the 
artery  may  encircle  the  femoral  opening  (likewise  any  pro- 
trusion through  it,  as  femoral  hernia)  to  gain  the  obturator 
canal  around  the  inner  side  of  the  femoral  opening.  (/) 
The  sciatic  artery  is  the  larger  terminal  branch  of  the  ante- 
rior trunk  of  the  internal  iliac.  It  passes  downward  to 
leave  the  pelvis  through  the  great  sacrosciatic  foramen,  be- 
low the  pyriformis  muscle.  For  its  continuation,  see  page 
613.  [g)  The  internal  pudic,  the  smaller  terminal  branch, 
passes  through  the  same  opening  with  the  sciatic,  but  above 
and  internal  to  it.  For  the  rest  of  the  artery,  see  page 
411. 


548  A  MANUAL  OF  ANATOMY. 

The  Posterior  Division  of  the  Internal  Iliac  Artery. 
{a)  The  iliolumbar  artery.  This  passes  outward  and 
upward  beneath  the  common  iliac  vessels  and  psoas  magnus 
muscle,  where  it  divides  into  two  main  trunks,  the  upper 
and  lower,  which  supply  the  adjoining  parts  and  anastomose 
with  the  last  lumbar,  gluteal,  and  deep  circumflex  iliac 
arteries.  {U)  The  two  lateral  sacral  pass  inward  across  the 
sacrum  to  anastomose  with  the  sacra  media,  to  supply  the 
surrounding  parts,  and,  penetrating  the  sacral  foramina,  to  be 
distributed  to  the  posterior  sacral  region,  {c)  The  gluteal. 
This  is  the  direct  continuation  of  the  posterior  trunk.  It 
leaves  the  pelvic  cavity  with  the  superior  gluteal  nerve 
through  the  great  sacrosciatic  foramen  above  the  pyriformis 
muscle.     For  its  distribution,  see  page  612. 

The  Internal  Iliac  Vein 

Is  formed  at  the  great  sacrosciatic  foramen  by  the  junc- 
tion of  the  gluteal,  sciatic,  and  internal  pudic  veins.  The 
venous  trunk  then  ascends  and  joins  the  external  iliac  vein 
at  the  sacro-iliac  articulation  to  form  the  common  iliac  vein. 
Besides  the  above  veins  the  internal  iliac  receives  the  lateral 
sacral,  iliolumbar,  obturator,  prostatic,  vesical,  hemor- 
rhoidal (vaginal  and  uterine  in  the  female)  veins. 

DISSECTION. 

Close  to  the  bladder  divide  the  remaining  ligaments,  vessels,  nerves,  ure- 
ters, and  vasa  deferentia  passing  to  it. 

Remove  the  bladder  and  open  it  from  its  apex  along  its  anterior  wall  to  the 
urethra,  and  this  also  for  its  entire  length  along  the  upper  surface. 

The  Opening's  of  the  Ureters. 

These  openings  are  three-fourths  of  an  inch  behind  the 
internal  urinary  meatus  and  the  same  distance  apart. 

The  beginning  of  the  urethra  is  called  the  internal 
meatus.     This  opening  lies  in  the  median  line,  three-fourths 


Fig.  114.  Dissection  OF  Pelvic  Wall  (Male)  FROM  THE  Side. — a,  Symphysis 
pubis.  6,  6,  Articular  surface  of  sacrum,  c,  Tuberosity  of  ischium,  rf,  Tip  of  coccyx. 
I,  Internal,  2,  External  iliac  artery.  3,  Gluteal  artery.  4,  Obturator  artery.  5,  Obtu- 
rator nerve.  6,  Lumbosacral  cord.  7,  First  sacral  nerve.  8,  Pyriformis  muscle. 
9,  Second,  10,  Third  sacral  nerves.  11,  Sciatic  artery.  12,  12,  Internal  pudic  artery. 
13,  Coccygeus  muscle  and  small  sacrosciatic  ligament.  14,  Internal  pudic  nerve. 
15,  Spine  of  ischium.  16,  Obturator  internus  muscle.  17,  (Deep)  dorsal  nerve  of 
penis.  iS,  (Superficial)  perineal  nerve.  19,  Attachment  of  great  sacrosciatic  ligament 
to  tuberosity  of  the  ischium. 


550  A  MANUAL  OF  ANATOMY. 

of  an  inch  behind  the  lower  margin  of  the  symphysis  and 
two  inches  above  the  level  of  the  perineum. 

Internal  Trigone. — This  is  the  triangular  area  mapped 
out  by  connecting  the  orifices  of  the  ureters  and  internal 
meatus  of  the  urethra  by  imaginary  lines. 

The  Urethra. 

This  is  the  membranous  tube  which  forms  the  outlet  to 
the  bladder  and  seminal  vesicles.  Its  length  is  approxi- 
mately six  inches  when  the  penis  is  relaxed.  Its  diameter 
to  the  size  of  the  penis  is  as  four  to  nine  (Otis). 

It  is  divided  into  the  prostatic  portion  (one  and  one- 
quarter  inches  long),  the  membranous  portion  (one-half 
to  three-fourths  of  an  inch  long),  and  the  spongy  portion 
(the  remainder  of  the  canal). 

The  prostatic  portion  pierces  the  prostate  from  base  to 
apex,  lying  nearer  the  anterior  than  the  posterior  surface 
of  the  gland. 

On  section  the  canal  is  U-shaped,  with  the  convexity 
forward  and  the  "  legs  "  backward. 

Within  the  prostatic  portion  the  following  structures  are 
found  : — 

(i)  The  verumontanum,  or  colliculus  seminaHs.  This 
is  a  vertical  elevation  along  the  posterior  wall  of  the  ure- 
thra, about  half  an  inch  long.  At  its  centre  is  the  opening 
of  a  blind  canal  (2),  the  sinus  pocularis,  or  the  uterus  mas- 
culinus.  Embryologically  related  to  the  female  uterus. 
Below  the  opening  of  the  sinus  pocularis  appear  (3)  the 
orifices  of  the  ejaculatory  ducts,  one  on  each  side  of  the 
median  line.  The  depressions  along  the  base  of  the  veru- 
montanum are  called  (4)  the  prostatic  sinuses,  and  into 
them  open  (5)  the  ducts  of  the  prostatic  glands. 

The  membranous  portion  of  the  urethra  is  the  only  fixed 


THE  ABDOMEN,  INTERIOR.  551 

part  of  the  canal.  It  is  held  in  place  by  the  two  layers  of 
the  triangular  ligament,  between  which  it  extends.  It  is 
surrounded  by  the  compressor  urethrae  muscle,  and  has  the 
glands  of  Cowper  in  close  relation  to  it. 

The  spongy  portion  of  the  urethra.  This  presents  two 
dilatations  :  one  at  its  beginning,  the  pars  bulbosa,  and 
one  at  its  termination,  the  fossa  navicularis. 

The  external  meatus  is  the  vertical  opening  of  the  ure- 
thra in  the  glans.  Along  the  spongy  portion  of  the  tube 
are  several  small  blind  depressions  opening  forward,  called 
lacunae.  One  of  these,  the  lacuna  magna,  is  situated  about 
an  inch  from  the  external  meatus,  and  may  catch  the  point 
of  a  sound  or  catheter.  The  urethra  shows  on  cross  sec- 
tion as  a  transverse  slit  in  the  membranous  and  spongy 
portions  of  the  urethra,  and  at  the  external  meatus  as  a 
vertical  slit. 

The  Sacral  Plexus.     Fig.  114. 

This  is  formed  by  the  union  of  the  Lumbosacral  Cord, 
(see  page  529),  and  the  anterior  divisions  of  the  first  three 
sacral  nerves  to  form  a  broad  ribbon  at  the  entrance  of  the 
great  sacrosciatic  foramen.  It  rests  upon  the  origin  of  the 
pyriformis  muscle.  The  fourth  sacral  nerve  enters  into  the 
plexus  indirectly  by  sending  a  branch  to  join  the  internal 
pudic  nerve.  The  fifth  sacral  nerve  has  no  part  in  the 
sacral,  but  enters  into  the  formation  of  the  coccygeal  plexus. 
The  fourth  sacral  nerve  has  most  of  its  filaments  distrib- 
uted independently  of  the  sacral  plexus,  to  the  skin  over  the 
lower  internal  portion  of  the  gluteus  maximus  muscle,  to  the 
integument  of  the  anus,  besides  furnishing  branches  to  the 
external  sphincter  ani,  coccygeus,  and  levator  ani  muscles. 

TJic  Brandies  of  the  Sacral  Plexus. 

{a)  The    superior    gluteal.      This    is    formed    by    two 


552  A  MANUAL   OF  ANATOMY. 

branches,  one  from  the  lumbosacral  cord  and  the  other  from 
the  first  sacral  nerve.  It  passes  out  of  the  pelvis  with  the 
gluteal  artery,  through  the  great  sacrosciatic  foramen  and 
above  the  pyriformis  muscle,  suppHes  the  gluteus  medius 
and  minimus,  between  which  it  runs  forward  to  terminate 
in  the  tensor  vaginae  femoris.  {U)  The  inferior  gluteal, 
formed  by  filaments  from  the  lumbosacral  cord,  the  first  and 
second  sacral  nerves,  leaves  by  the  same  foramen  as  the 
above,  only  below  the  pyriformis  muscle  (where  it  is  usually 
contained  in  the  same  sheath  with  the  small  sciatic  nerve,  giv- 
ing rise  to  the  statement  that  it  is  a  branch  of  the  small  sci- 
atic), and  terminates  in  the  gluteus  maximus  muscle,  {c) 
The  branch  to  the  pyriformis  muscle  is  from  the  second  and 
third  sacral  nerves,  {d')  The  nerve  to  the  quadratus  femoris 
arises  from  the  third  sacral  nerve,  passes  through  the  great 
sacrosciatic  foramen  below  the  pyriformis  muscle,  descends 
in  front  (anterior  to)  the  obturator  internus  and  gemelli 
muscles  to  be  distributed  to  the  anterior  surface  of  the 
quadratus  femoris  muscle.  In  its  passage  over  the  hip- 
joint  it  sends  a  branch  to  it.  {/)  The  small  sciatic  nerve 
comes  from  the  posterior  surface  of  the  second  and  third 
sacral  nerves,  makes  its  exit  from  the  pelvis  through  the 
great  sacrosciatic  foramen  below  the  pyriformis  muscle. 
For  the  rest  of  its  course,  see  page  604.  (/)  The  nerve 
to  the  obturator  internus  arises  from  the  second  and  third 
sacral  nerves,  goes  out  through  the  great  sacrosciatic  fora- 
men under  the  pyriformis,  re-enters  the  pelvis  through  the 
smaller  sacrosciatic  foramen,  and  is  distributed  to  the  mus- 
cle from  which  it  is  named,  (^g)  The  internal  pudic  arises 
by  three  roots  from  the  second,  third,  and  fourth  sacral 
nerves,  takes  the  same  course  as  the  nerve  above  until  the 
pelvis  is  re-entered,  it  then  follows  along  with  the  internal 
pudic    artery  through    the    canal  (Alcock's)  beneath    the 


THE  ABDOMEN,  INTERIOR.  553 

obturator  fascia,  to  supply  the  structures  of  the  perineum, 
see  page  413.  (//)  The  great  sciatic  nerve.  This  is  the 
termination  of  the  sacral  plexus.  It  is  the  largest  nerve  in 
the  body.  From  its  origin  it  passes  outward  through  the 
great  sacrosciatic  foramen  below  the  pyriformis  muscle  into 
the  gluteal  region  ;    for  further  course,  see  page  610. 

The  sacral  gangliated  cord  is  the  continuation  of  the 
lumbar  cord  from  behind  the  iliac  vessels  to  the  central 
ganglion  (impar)  over  the  front  of  the  coccyx  ;  there  are 
four  small  ganglia  usually  in  the  course  of  the  cord,  but 
may  be  fewer. 


554  A  MANUAL   OF  ANA  TO  MY. 

THE  LOWER  EXTREMITY,  Anterior. 

Landmarks.     Fig.  87,  98,  115. 

The  landmarks  at  the  lower  part  of  the  abdomen  belong 
also  to  the  lower  extremity.  They  are  the  symphysis,  body, 
and  spine  of  the  pubes,  Poupart's  ligament,  the  anterior 
superior  spine  and  crest  of  the  ilium.  Below  the  crest  of 
the  ilium  to  the  outer  part  of  the  thigh  is  the  great  tro- 
chanter. Its  upper  border  is  on  a  level  with  the  centre  of 
the  hip-joint. 

Nelaton's  line  is  drawn  from  the  anterior  superior  spine 
of  the  ilium  to  the  tuberosity  of  the  ischium,  and  it  crosses 
normally  to  the  top  of  the  great  trochanter. 

About  the  knee  the  prominent  condyles  of  the  femur,  the 
tuberosities  of  the  tibia,  the  head  of  the  fibula,  and  the 
patella  should  all  be  examined.  Especially  should  the 
var}-ing  positions  of  the  patella  in  flexion  and  extension  of 
the  leg  be  appreciated.  The  ridge  of  the  tibia  along  the 
front  of  the  leg  produces  the  shin,  and  as  the  bone  is  cov- 
ered by  skin  and  subcutaneous  fascia  alone,  injuries  here  are 
liable  to  produce  wounds  through  them  to  the  bone. 

At  the  ankle  the  prominent  malleoli  are  recognized.  The 
internal  is  in  front  of  the  external  and  does  not  reach  so  low 
down.  Measurements  for  difference  in  the  limbs  are  usu- 
ally from  the  anterior  superior  spines  of  the  ilium  to  the 
internal  malleoli.      See  page  434. 

At  the  foot  the  most  prominent  bony  parts  are  the  head 
of  the  astragalus  (if  the  foot  is  fully  extended). 

Behind  the  foot  is  the  os  calcis,  which  can  be  felt  on  both 
sides.  On  the  inside  is  the  prominent  tubercle  of  the  sca- 
phoid and  head  of  the  first  metatarsal  bone.  The  susten- 
taculum tali  of  the  os  calcis  lies  in  front  of  and  one  inch  below 


1p..^''?"q^^;    Dissection    of    Thigh,   Anterior.-i,  Falciform  process  of  fascia 

Poupart's     ilTem°''r''^^-T  ^'  ^^^^^'^'^'a-     4.  Aponeurosis  of  ext'ernafobl^ue      5 
roupart  s    ligHmeiit       0,   6,   Long,    or    internal,    saphenous    vein       -    S    Cutanpons 

cutrneous°nerve:'"'  '"'""°"^  "^"^     ''  Superficiafexternal  pudic  vein''  fo"  M-ddll 


556  A  MANUAL   OF  ANATOMY. 

the  internal  malleolus.  The  tubercle  of  the  scaphoid  is  one 
and  one-fourth  of  an  inch  in  front  of  the  same  point.  On 
the  outer  side  of  the  foot  the  os  calcis,  cuboid,  and  base  of 
the  fifth  metatarsal  bones  can  be  felt. 

\ 

DISSECTION. 
Incision. — (i)   From  the  middle  of  Poupart's  ligament  down  the  front  of 
the  thigh  to  below  the  patella. 

(2)   Two  short  transverse  cuts  at  the  lower  end  of  (i). 
Remove  the  skin  only,  turning  it  off  laterally  as  far  as  possible. 

The  Superficial  Fascia.      Fig.  115. 

This  fascia  varies  in  thickness  with  the  amount  of  adipose 
tissue  present.  It  is  described  as  consisting  of  two  layers, 
the  superficial  and  deep,  but  this  distinction  can  be  readily 
made  only  in  the  upper  third  of  the  thigh.  Within  the 
superficial  fascia  are  contained  the  superficial  vessels,  nerves, 
and  lymphatics. 

The  superficial  layer  of  the  fascia  passes  up  over  Pou- 
part's ligament  to  become  continuous  with  a  similar  layer  of 
the  abdomen,  behind  with  the  fascia  of  the  buttocks,  and 
below  passes  into  that  covering  the  leg. 

The  deep  layer  is  only  demonstrated  with  ease  in  the 
upper  third  of  the  thigh.  It  consists  of  a  thickening  of 
the  under  surface  of  the  superficial  fascia  and  is  attached 
above  to  the  crest  of  the  ilium,  Poupart's  ligament,  spine, 
crest,  and  front  of  the  pubes ;  internally  and  externally  it 
blends  with  the  fascia  lata,  centrally  it  covers  over  the 
saphenous  opening  and  is  strongly  attached  to  its  outer  and 
lower  margins  and  loosely  to  its  inner  margin,  forming  the 
cribriform  fascia. 


DISSECTION. 
Trace  the  superficial  arteries,  veins,  and  nerves.     Locate  the  femoral  lym- 
phatics. 


THE  LOWER  EXTREMITY,  ANTERIOR.  557 

The  Superficial  Arteries.      Figs.  88,  115. 

Are  the  superficial  external  pudic.  The  superficial 
epigastric.  See  page  436.  The  superficial  circumfiex 
iliac.      See  page  572. 

Superficial  t^vig-s  of  the  muscular  branches  of  the 
femoral  are  seen  after  penetrating  the  fascia  lata  along  the 
front  of  the  thigh. 

The  superficial  branch  of  the  anastomotica  magna  will 
be  found  on  the  inner  side  of  the  knee  with  the  internal 
saphenous  nerve. 

The  Superficial  Veins.      Fig.  115. 

The  internal  saphenous  vein  is  found  at  the  inner  side 
of  the  knee  as  it  ascends  from  the  leg.  It  passes  upward 
to  enter  the  saphenous  opening  (passing  through  the  cribri- 
form fascia),  and  empty  into  the  femoral  vein.  In  its  course 
up  the  thigh  it  receives  the  external  and  internal  cutaneous 
femoral  veins,  and  at  the  saphenous  opening  the  superficial 
external  pudic,  epigastric,  and  circumflex  iliac  veins. 

The  Superficial  Nerves.     Fig.  115. 

These  will  be  demonstrated  as  the  fascia  lata  is  cleaned, 
though  filaments  of  the  main  branches  will  be  found  at  this 
stage.  It  is  not  advisable  to  delay  the  dissection  to  look 
especially  for  them.  They  are  branches  from  the  last 
dorsal,  between  the  crest  of  the  ilium  and  great  trochanter  ; 
External  Cutaneous ;  the  middle  and  internal  cutaneous 
from  the  Anterior  Crural ;  the  Genitocrural  (see  page  53^); 
and  the  Ilio-inguinal  (see  page  5  30). 

The  Femoral  Lymphatics.      Fig.  115. 

These  will  be  found  below  the  middle  of  Poupart's  liga- 
ment and  grouped  about  the  saphenous  opening.  They 
receive  the  drainage  of  the  superficial  area  of  the  lower 


558  A  MANUAL   OF  ANA  TOMY. 

extremity  represented  by  the  distribution  of  the  internal 
saphenous  vein  (internal,  anterior,  and  posterior  area  of 
lower  extremity). 

The  Prepatellar  Bursa 

Will  be  found  over  the  patella,  between  it  and  the  deep 
fascia.      A  vertical  incision  will  open  into  the  bursa. 

DISSECTION. 

Remove  all  of  the  superficial  fascia,  leaving  the  vessels  and  nerves  lying 
upon  the  fascia  lata. 

Recognize  the  deep  layer  of  the  superficial  fascia  and  its  attachments, 
then  remove  it  carefully  and  expose  the  saphenous  opening,  and  vein  passing 
through  it.  Save  the  denser,  curved  outer  band  and  the  thinner  inner  por- 
tion of  the  fascia  bounding  the  saphenous  opening. 

The  Fascia  Lata,  Anterior  Portion.      Figs.  115,  116. 

This  is  a  strong  tube  of  membrane  enclosing  the  thigh. 
Attached  below  to  the  bony  points  about  the  knee — con- 
dyles of  femur,  patella,  tuberosities  of  tibia,  head  of  the 
fibula.  Above,  anteriorly,  Poupart's  ligament,  spine,  crest, 
and  front  of  the  pubes  (iliac  portion).  The  pubic  portion 
is  under  the  iliac  portion  and  is  attached  to  the  iliopectineal 
line,  and  externally  blends  with  the  iliac  fascia  from  the 
pelvis.  (See  page  525.)  Internally,  to  the  rami  of  the 
pubes  and  ischium.      Posteriorly,  see  page  600. 

{a)  Intermuscular  Septa. — A  strong  one  is  found  ex- 
ternally between  the  vastus  and  the  biceps  muscles  attached 
to  the  external  lip  of  the  linea  aspera.  A  less  distinct 
septum  is  found  in  front  of  the  adductor  muscles,  and  a 
third  one  behind  them.  From  the  under  surface  of  the  fascia 
lata  there  also  extend  off  processes  to  enclose  all  the 
muscles  of  the  thigh  in  separate  compartments. 

{U)  The  Iliotibial  Band. — This  is  a  reinforcement  of  the 
transverse  fibres  of  the  fascia   lata  along  the  outer  side  of 


560  A  MANUAL   OF  ANATOMY. 

the  thigh,  by  vertical  fibres  extending  from  the  anterior 
portion  of  the  crest  of  the  iHum  to  the  head  of  the  fibula 
and  external  tuberosity  of  the  tibia.  Into  the  upper  fourth 
of  this  band  the  tensor  vaginae  femoris  is  inserted. 

(c)  Internal  Process. — An  internal  process  of  the  fascia 
lata  extends  from  the  notch  and  inferior  anterior  iliac  spine, 
along  the  inner  surface  of  the  tensor  vaginse  femoris  muscle, 
to  join  the  iliotibial  band  just  below  the  insertion  of  the 
muscle. 

(^)  Tlie  Saphenous  Opening. — The  confusion  in  the 
descriptions  of  the  saphenous  opening  all  arise  from  the 
fact  that  the  opening  does  not  exist  in  the  normal  condition. 
It  is  a  product  of  a  femoral  hernia  or  of  the  dissector. 
Different  dissectors  manufacture  different  sorts  of  openings, 
according  to  their  preconceived  ideas  derived  from  the 
descriptions  they  have  read,  or  as  a  result  of  careless  dis- 
section, or  from  the  varying  conditions  of  the  fascia  itself, 
(for  not  all  fasciae  have  the  margins  of  the  opening  equally 
plain). 

Stated  briefly,  the  saphenous  opening  is  simply  a  gap 
produced  by  the  separation  of  the  iliac  and  pubic  portions 
of  the  fascia  lata,  the  iliac  portion  having  the  external  and 
more  superficial  attachment  (Poupart's  ligament,  spine  of 
pubes),  the  pubic  portion  having  the  more  internal  and 
deep  attachment  (to  the  iliopectineal  line  and  iliac  fascia 
behind  the  femoral  vessels).  Through  this  gap  passes  the 
internal  saphenous  vein,  superficial  external  pudic  and 
superficial  epigastric  arteries,  and  the  genitocrural  nerve. 

The  opening  is  about  one '  inch  below  the  inner  portion 
of  Poupart's  ligament,  its  vertical  diameter  one  and  one- 
fourth  or  one-half  inch,  its  transverse,  one-half  to  three- 
fourths  of  an  inch.  These  measurements  are  after  dis- 
section.     The  outer  or  iliac  portion,  bounding  the  opening. 


THE  LOWER  EXTREMITY,  ANTERIOR.  561 

is  a  somewhat  thickened  band  extending  from  the  spine  of 
the  pubes  and  the  inner  part  of  Poupart's  Hgament,  out- 
ward and  downward  under  the  saphenous  vein  to  blend 
with  the  pubic  portion  on  the  inner  side  of  the  opening. 
This  curved  free  border  of  the  iliac  portion  of  the  fascia 
lata  is  the  falciform  lig-ament  or  process. 

There  is  no  band  on  the  inner  side  of  the  opening  as  on 
the  outer,  because  the  sheet  of  fascia  (pubic  portion)  ex- 
tends upward  and  outward,  under,  behind  the  femoral  ves- 
sels, forming  an  almost  level  plane  of  fascia  with  which  the 
falciform  process  blends  at  its  lower  portion.  This  pubic 
portion  of  the  fascia  lata  helps  to  form  the  posterior  cover- 
ing for  the  femoral  vessels.  The  opening  is  covered  over 
by  the  deep  layer  of  the  superficial  fascia,  which  is  firmly 
attached  to  the  falciform  process  (outer  and  lower  margin 
of  the  opening)  and  but  slightly  to  the  pubic  or  inner  mar- 
gin of  the  fascia  lata. 

This  firm  attachment  of  the  cribriform  fascia  to  the  outer 
and  lower  margin  of  the  opening  and  its  loose  attachment 
to  the  pubic  portion  explains  (at  least  partially)  why  a 
femoral  hernia  takes  an  upward  and  inward  course  as  soon 
as  it  leaves  the  saphenous  opening. 

This  covering  to  the  saphenous  opening  is  called  the 
cribriform  fascia,  because  it  is  perforated  by  the  internal 
saphenous  vein,  superficial  external  pudic  and  superficial 
epigastric  arteries,  and  (sometimes)  the  genitocrural  nerve. 

The  External  Cutaneous  Nerve.      Fig.   115. 

This  will  be  found  as  it  issues  from  under  Poupart's  liga- 
ment close  to  the  anterior  superior  spine  of  the  ilium.  Its 
course  is  downward  along  the  outer  side  of  the  thigh,  in  a 
canal  formed  by  the  fascia  lata,  for  four  or  five  inches,  it 
then  becomes  superficial  and  supplies  the  integument  of  the 
;,6 


562  A  MANUAL   OF  ANATOMY. 

anterior  and  outer  surfaces  of  the  thigh  nearly  to  the  knee. 
Just  below  the  spine  of  the  ilium  it  gives  off  a  branch 
which  turns  backward  to  supply  the  integument  over  the 
great  trochanter. 

The  Internal  Cutaneous  Nerve.      Figs.  115,  117. 

It  descends  across  the  femoral  artery  and  divides  into 
two  branches  :  an  anterior,  which  pierces  the  fascia  lata  at 
the  middle  and  lower  thirds  of  the  thigh  and  supplies  the 
integument  of  the  inner  anterior  surface  of  the  lower  third 
of  the  thigh. 

It  descends  across  the  vessels  and  gives  off  branches 
which  perforate  the  fascia  lata  at  various  levels  to  supply 
the  integument  of  the  inner  surface  of  the  thigh.  The 
two  terminal  branches  are  described  as  the  anterior  and 
posterior  branches.  The  anterior  is  distributed  to  the 
front  of  the  lower  third  of  the  thigh  and  knee,  while  the 
posterior  branch  extends  downward  to  the  upper  third  of 
the  back  of  the  leg. 

The  Middle  Cutaneous  Nerve.      Figs.   115,  117. 

May  exist  as  a  single  or  double  trunk.  It  (or  one  of  the 
divisions)  usually  pierces  the  sartorius  muscle,  then  the 
fascia  lata  at  the  upper  and  middle  thirds  of  the  thigh,  and 
supplies  the  integument  of  the  front  and  inner  sides  of  the 
thigh  to  the  knee. 

DISSECTION. 
Carefully  remove  the  fascia  lata,  with  the  superficial  vessels  and  nerves,  from 
the  front  of  the  thigh  ;   leaving  Poupart's   ligament   intact    above  ;   the  ilio- 
tibial  band  on  the  outside  ;  and  exposing  the  gracilis  muscle  on  the  inside. 

Sartorius.     Fig.  117. 

Origin. — From  the  anterior  superior  spine  of  the  ilium 
and  the  upper  part  of  the  notch  below. 


Fig.  117.  Dissection  of  Thigh,  Anterior.— i,  Iliacus  muscle.  2,  Poupart's 
ligament.  3,  Deep  circumflex  iliac  artery  (femoral  artery  has  been  pulled  lower  than 
natural).  4,  Sartorius  muscle.  5,  Anterior  crural  nerve.  6,  Femoral  vein.  7,  The 
profunda  artery.  8,  Femoral  artery.  9,  Rectus  femoris  muscle.  10,  The  external 
cutaneous  nerve.  11,  Middle  cutaneous  nerve.  12,  Vastus  externus  muscle.  13, 
Patella.  14,  Vastus  iiiternus  muscle.  15,  Internal  cutaneous  nerves.  16,  Gracilis 
muscle.  17,  Adductor  longus  muscle.  18,  Pectineus  muscle.  19,  Deep  external 
pudic  artery.  20,  Spermatic  cord.  21,  Penis.  22,  Pyramidalis  muscle  turned  down- 
ward. 23,  Long,  or  internal,  saphenous  nerve  crossing  the  femoral  artery.  24,  Cru- 
reus  muscle.    25,  The  external  circumflex  artery. 


564  A  MANUAL  OF  ANA  TOMY. 

hisertion. — Into  the  front  of  the  tibia  just  internal  to  the 
tubercle  by  an  inverted  J -shaped  tendon,  the  curve  of  the 
J  hooking  over  the  tendons  of  the  gracilis  and  semitendino- 
sus  muscles.  Also,  into  the  deep  fascia  over  the  lower 
part  of  the  knee-joint  and  upper  part  of  the  leg. 

Nerve  Supply. — The  anterior  crural,  through  its  middle 
cutaneous  branch,  which  pierces  the  muscle  at  its  upper  and 
middle  thirds. 

Actions. — To  flex  the  thigh  on  the  abdomen,  to  flex  the 
leg  on  the  thigh,  to  rotate  the  thigh  outward,  to  rotate  the 
leg  (when  semiflexed)  inward.  It  has  a  slight  action  of 
abduction,  but  no  action  tending  to  cross  (adduct)  the 
thighs.  Acting  from  below  it  will  flex  the  pelvis  on  the 
femur,  and  slightly  rotate  it  toward  the  opposite  side. 

Tensor  Vag-inse  Pemoris.     Figs.  117,  118. 

Origin. — From  the  anterior  one  inch  of  the  outer  lip  of 
the  crest  of  the  ilium,  the  upper  portion  of  the  notch  below, 
and  from  the  fascia  covering  the  gluteus  medius  (a  portion 
of  the  fascia  lata). 

Insertion. — Into  the  inner  surface  of  the  fascia  lata  at  its 
upper  fourth,  and  by  the  continuation  of  the  fascia,  under 
the  name  of  the  iliotibial  band,  into  the  head  of  the  fibula 
and  external  tuberosity  of  the  tibia.  The  muscle  at  its  in- 
sertion is  found  between  two  laminse  of  the  fascia  lata.  An 
external  part  of  the  fascial  covering  of  the  thigh,  which 
reaches  up  to  the  crest  of  the  ilium  ;  and  an  internal  layer, 
which  passes  up  to  the  anterior  inferior  spine  of  the  ilium 
and  the  tendons  of  the  rectus  muscle. 

Nerve  Supply. — The  superior  gluteal,  which  comes  for- 
ward between  the  gluteus  medius  and  minimus,  and  enters 
the  posterior  surface  of  the  muscle. 

Action. — To  tense  the  fascia   lata,  to   flex  the   thigh,  to 


THE  LOWER  EXTREMITY,  ANTERIOR.  565 

abduct  the  thigh,  to  rotate  the  thigh  inward  ;  through  the 
iliotibial  band,  to  flex  the  leg,  to  rotate  the  leg  outward, 
when  flexed. 

Acting  from  below  it  preserves  the  horizontal  position  of 
the  pelvis  upon  the  femur  (in  this  connection  acting  with 
the  gluteus  maximus),  and  rotates  it  to  the  same  side. 

Rectus  Femoris.     Fig.  117. 

Orighi. — By  the  straight  (anterior)  tendon  from  the  ante- 
rior inferior  spine  of  the  ilium,  by  the  reflected  (posterior) 
tendon  from  the  outer  surface  of  the  ilium  just  above  the 
acetabulum. 

Insertion. — Into  the  upper  border  of  the  patella. 

Nerve  Supply. — The  anterior  crural. 

Action. — To  extend  the  leg  on  the  thigh,  or  vice  versa ; 
to  flex  the  thigh  on  the  abdomen  or  the  reverse. 

Pectineus.     Figs.  117,  120. 

Origin. — From  the  iliopectineal  line  and  the  triangular 
surface  of  bone  in  front  of  it,  between  the  iliopectineal 
(pubal)  eminence  and  the  spine  of  the  pubes.  From  the 
under  inner  surface  of  the  fascia  lata  covering  the  muscle. 

Insertion. — Into  a  line  extending  from  the  back  of  the 
lesser  trochanter  to  the  linea  aspera  of  the  femur. 

Nerve  Supply. — The  obturator,  anterior  crural  (constant), 
and  the  accessory  obturator  (when  present). 

Action. — To  flex  the  thig-h,  to  adduct  the  thigh,  to  rotate 
the  thigh  slightly  externally  when  it  is  partially  flexed,  but 
if  the  thigh  is  kept  extended  it  will  rotate  it  internally  in  the 
same  way  that  the  iliopsoas  muscle  does.  The  explanation 
is  this  :  the  centre  of  motion  is  at  the  hip-joint  ;  the  mus- 
cular attachments  are  to  the  shaft  of  the  femur  two  inches 
external  to  the  centre  of  motion  ;  flexion  being  resisted  the 


566  A  MANUAL  OF  ANATOMY. 

great  trochanter  will  be  raised ;  this  produces  internal 
rotation  of  the  shaft  of  the  femur.  The  iliopsoas  and  pec- 
tineus  have  this  action. 

Adductor  Long-us.     Figs.  117,  119. 

Origin. — From  the  front  of  the  body  of  the  pubes  just 
under  the  crest. 

Insertion. — At  the  middle  third  of  the  femur,  into  the 
inner  lip  of  the  linea  aspera. 

Nerve  Supply. — The  obturator  nerve  through  its  anterior 
division. 

Action. — To  adduct,  flex,  and  rotate  the  femur  outward. 
If  the  femur  is  the  fixed  point,  it  will  flex  the  pelvis  and 
rotate  it  to  the  same  side. 

Gracilis.     Figs.  117,  119. 

Origin. — From  the  inner  margin  of  the  rami  of  the  pubes 
and  ischium,  and  from  the  lower  half  of  the  symphysis 
pubis. 

Insertion. — By  a  long  slender  tendon  into  the  inner  sur- 
face of  the  tibia  in  the  angle  formed  by  the  tendon  of  the 
sartorius. 

Nerve  Supply. — A  branch  from  the  anterior  division  of  the 
obturator  nerve. 

Action. — To  adduct  the  thigh,  to  flex  the  leg ;  when  the 
leg  is  flexed  to  rotate  it  internally. 

The  Internal  Saphenous  Nerve.     Figs.  117,  119. 

The  longest  branch  of  the  anterior  crural  nerve.  Be- 
ginning just  below  Poupart's  ligament  where  the  anterior 
crural  nerve  breaks  up  into  its  terminal  branches,  the  inter- 
nal or  long  saphenous  nerve  descends  along  the  outer  side 
of  the  femoral  artery  through  Scarpa's  triangle,  then  enters 
Hunter's  canal  with  the  femoral  vessels.     In  the  canal  the 


568  A  MANUAL   OF  ANA  TOMY. 

nerve  crosses  over  the  front  of  the  artery  from  its  outer  to 
its  inner  side.  Leaving  the  femoral  artery,  when  it  turns 
backward  through  the  opening  in  the  adductor  magnus,  the 
nerve  continues  downward  between  the  tendons  of  the 
sartorius  (in  front)  and  the  gracilis  (behind)  and  becomes 
superficial  just  below  the  inner  side  of  the  knee  joint 
Here  it  joins  the  internal  saphenous  vein,  which  it  accom- 
panies along  the  inner  side  of  the  leg  to  the  ankle,  and 
terminates  a  short  distance  below  the  internal  malleolus. 

While  under  cover  of  the  sartorius  muscle  the  internal 
saphenous  nerve  gives  off  the  patellar  branch  which  pierces 
the  sartorius  and  runs  downward  and  forward  to  the  front 
of  the  knee.  It  supplies  the  integument  over  the  inner 
side  of  the  knee,  leg,  and  ankle. 

The  Nerve  to  the  Pectineus  Muscle. 

This  is  a  small  but  constant  branch  given  off  from  the 
anterior  crural  just  under  Poupart's  ligament.  It  passes 
downward  and  inward  behind  the  sheath  of  the  femoral 
vessels,  with  which  it  is  closely  united  to  the  front  of  the 
pectineus  muscle. 

The  Muscular  Branches  of  the  Anterior  Crural.  Figs. 
117,  119,  120. 
They  are  distributed  to  the  sartorius  (usually  from  the  mid- 
dle cutaneous),  rectus  femoris,  vastus  externus  and  internus, 
crureus,  and  pectineus  muscles.  The  hip  joint  receives  a 
branch  from  the  nerve  to  the  rectus.  The  articular  branches 
to  the  knee  joint  are  filaments  from  the  branches  to  the 
rectus,  vasti,  and  crureus  muscles,  which  passing  onward 
through  the  muscles  terminate  in  the  upper  part  of  the 
capsule  and  synovial  membrane  of  the  knee  joint. 

Scarpa's  Triangle.      Fig.  1 1 7. 

This  is  a  triangular  space   located  upon  the  front  of  the 


THE  LOWER  EXTREMITY,  ANTERIOR.  569 

upper  part  of  the  thigh.  It  is  formed  by  the  sartorius 
muscle  upon  the  outside,  the  adductor  longus  on  the  inside, 
and  Poupart's  ligament  above,  which  forms  the  base  of  the 
triangle. 

The  "floor"  of  the  space  is  formed  from  without  in- 
ward by  the  lower  portion  of  the  iliacus,  the  tendon  of  the 
psoas  magnus,  the  pectineus,  the  adductor  longus,  and  (in 
thin  people)  the  adductor  brevis  muscles.  The  triangle  is 
crossed  from  the  middle  of  the  base  to  the  apex  at  the 
junction  of  the  sartorius  and  adductor  longus  by  the 
femoral  vessels  and  the  anterior  crural  nerve  and  its 
branches. 

The  relations  of  these  structures  under  Poupart's  liga- 
ment is  nerve,  artery,  and  vein  from  without  inward. 

Internal  to  the  vein  is  the  femoral  opening  or  canal.  See 
below,  also  page  525. 

At  the  apex  of  the  triangle  the  vein  turns  backward  so 
as  to  lie  nearly  behind  the  artery,  while  the  branches  of 
the  nerve  are  to  the  outside  of  and  in  front  of  the 
vessels. 

The  triangle  is  covered  by  the  fascia  lata,  the  two  layers 
of  the  superficial  fascia,  and  the  integument. 

The  Femoral  Canal 

Is  the  space  left  within  the  femoral  sheath  (at  the  inside 
of  the  femoral  vein,  between  the  vein  and  Gimbernat's 
ligament  and  the  conjoined  tendon).  There  is  no  canal 
unless  made  by  the  descent  of  a  femoral  hernia  or  by  the 
dissector.  When  a  femoral  hernia  develops  it  leaves  the 
abdomen  through  the  femoral  opening  at  the  inner  side  of 
the  terminus  of  the  external  iliac  vein,  descends  along  the 
inside  of  the  femoral  vein,  and  makes  its  appearance  through 
the  saphenous  opening. 


570  A  MANUAL  OF  ANATOMY. 

The  Femoral  Artery.     Figs.  1 1 7  to  1 20. 

This  is  that  portion  of  the  great  arterial  trunk  to  the 
lower  extremity  which  extends  from  beneath  Poupart's 
ligament  to  the  opening  in  the  adductor  magnus  muscle. 
It  is  a  continuation  of  the  external  iliac  above,  and  is  con- 
tinued as  the  popliteal  below. 

The  course  of  the  artery  is  indicated  by  a  line  drawn 
from  the  mid-point  between  the  anterior  superior  iliac 
spine  and  the  symphysis  pubis  to  the  adductor  tubercle, 
the  thigh  being  slightly  abducted,  flexed,  and  rotated 
outward. 

The  femoral  artery  passes  through  Scarpa's  triangle  from 
the  middle  of  its  base  to  its  apex,  and  through  Hunter's 
canal. 

Its  relations  will  be  considered  in  these  localities. 

Relations  of  the  Femoral  Artery. — Scarpa's  triangle.  See 
above.  Here  the  artery  is  centrally  placed  between  the 
femoral  vein  on  the  inside  and  the  anterior  crural  nerve  and 
its  branches  on  the  outside. 

The  vein  as  it  descends  passes  to  a  deeper  level  than  the 
artery,  so  that  at  the  apex  of  the  triangle  it  comes  to  occupy 
a  position  behind  and  internal  to  the  artery. 

The  internal  cutaneous  branch  of  the  anterior  crural 
nerve  crosses  over  the  front  of  the  artery  in  the  lower  part 
of  the  triangle,  while  the  internal  saphenous  nerve  con- 
tinues along  the  outer  side  of  the  vessel. 

In  this  part  of  its  course  the  artery  rests  at  its  upper 
part  upon  the  tendon  of  the  psoas  magnus  (which  separates 
it  from  the  pelvis  and  the  capsule  of  the  hip-joint)  the 
nerve  to  the  pectineus  and  that  muscle  itself,  At  its  lower 
portion,  upon  the  profunda  artery  and  vein  (which  inter- 
vene between  the  femoral  and  the  pectineus  muscle),  and 
the  adductor  longus.     In  thin  people  a  small  portion  of  the 


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572  A  MANUAL  OF  AAA  TO  MY, 

adductor  brevis  muscle  appears  between  the  pectineus  and 
adductor  longus. 

The  artery  is  covered  by  the  integument,  superficial  fascia, 
fascia  lata,  and  is  crossed  by  some  small  cutaneous  nerve 
filaments  and  veins. 

Hunter's  Canal. — See  page  575.  In  its  passage  through 
this  triangular  shaped  canal  the  femoral  artery  lies  between 
the  vastus  internus  on  the  outside,  the  adductor  longus 
and  magnus  on  the  inside,  and  beneath  the  aponeurotic 
membrane  which  unites  these  muscles.  The  femoral  vein 
accompanies  the  artery,  being  placed  behind  and  internal  to 
the  artery  at  the  upper  part  of  the  canal,  and  behind  and 
slightly  external  to  the  artery  at  the  opening  in  the  adductor 
magnus. 

The  internal  saphenous  nerve  also  passes  through  the 
canal  with  the  artery  and  crosses  it  from  the  outside  to  the 
inside  ;  it  leaves  the  artery  at  the  lower  part  of  the  canal  by 
passing  in  front  of  the  tendon  of  the  adductor  magnus 
muscle,  while  the  artery  passes  through  the  opening  in  the 
same.  In  front  of  the  artery  (in  addition  to  the  aponeurotic 
covering  and  the  internal  saphenous  nerve)  are  the  sartorius 
muscle,  the  fasciae,  and  integument. 

TJie  BrancJics  of  the  Femoral  Artery. 

(i)  The  superficial  epigastric.  See  page  436.  This 
is  a  small  branch  from  the  front  of  the  femoral  just  below 
Poupart's  ligament.  It  pierces  the  fascia  lata,  then  turns 
upward  and  inward  on  to  the  abdomen  to  ramify  in  the 
subcutaneous  tissue  as  high  as  the  umbilicus. 

(2)  The  superficial  circunifiex  iliac. — This  is  another 
small  branch  from  the  superficial  epigastric,  or  from  the 
femoral  close  to  it.  It  passes  through  the  fascia  lata,  runs 
outward  just  below  Poupart's  ligament  and  breaks  up  into 
branches   which  supply  the    superficial   tissues  about  the 


THE  LOWER  EXTREMITY,  ANTERIOR.  573 

crest  of  the  ilium.  In  its  course  it  gives  off  twigs  to  the 
iliacus,  sartorius  muscles,  and  the  inguinal  lymphatic 
glands. 

(3)  The  superficial  (superior)  external  pudic  arises 
from  the  inner  side  of  the  femoral,  passes  through  the  fascia 
lata  or  the  saphenous  opening,  extends  upward  and  inward 
to  the  lower  part  of  the  abdomen,  where  it  meets  its  fellow 
from  the  other  side.  As  it  is  opposite  the  side  of  the  root 
of  the  penis  it  gives  off  the  superficial  dorsal  artery  to 
that  organ. 

(4)  The  deep  (inferior)  external  pudic. — A  branch  in 
common  with  the  above,  or  just  below  it,  from  the  inner 
side  of  the  femoral.  It  takes  a  course  inward  across  the 
pectineus  and  adductor  longus  muscles  (to  which  it  gives 
muscular  branches)  passes  through  the  fascia  lata  at  the 
inner  border  of  the  adductor  longus,  breaks  up  into 
branches  which  supply  the  scrotum  (labium  in  the  female) 
and  the  inner  side  of  the  thigh. 

(5)  The  deep  femoral.     See  page  579. 

(6)  The  anastomotica  magna. — This  artery  is  given  off 
from  the  femoral  just  before  it  turns  backward  through  the 
femoral  opening,  at  the  lower  end  of  Hunter's  canal. 

It  divides  into  two  branches,  the  superficial  and  deep. 
The  former  takes  a  superficial  course  along  with  the  long 
or  internal  saphenous  nerve  to  the  inner  side  of  the  knee, 
while  the  latter,  the  deep  branch,  takes  a  deeper  course 
through  the  fibres  of  the  vastus  internus  muscle  in  front 
of  the  tendon  of  the  adductor  magnus  to  the  deeper  parts 
about  the  knee.  Both  of  these  arteries  enter  into  an  an- 
astomosis with  the  internal  articular  branches  from  the 
popliteal  ;  the  superficial  with  the  inferior,  and  the  deep 
with  the  superior,  internal  articular  branches. 

(7)  The  muscular  branches. — These  are  small  branches, 


574  A  MANUAL   OF  ANATOMY. 

varying  in  number,  to  the  muscles  in  relation  to  the  femoral 
artery  in  its  course. 

The  Femoral  Vein. 

The  femoral  vein  begins  at  the  opening  in  the  adductor 
magnus,  where  it  is  the  continuation  of  the  popliteal  vein, 
and  ends  under  Poupart's  ligament,  beyond  which  point  the 
venous  trunk  is  continued  as  the  external  iliac  vein.  The 
relations  of  the  femoral  vein  have  been  sufficiently  given 
with  those  of  the  artery,  q.  v.,  page  570. 

The  Tributaries. — (i)  The  venae  comites  of  the  anasto- 
motica  magna  artery.  (2)  The  venae  comites  of  the  mus- 
cular branches.  (3)  The  deep  femoral  vein.  The  deep 
femoral  vein  retraces  the  course  of  the  profunda  artery, 
receiving  as  it  does  so  the  venae  comites  corresponding  to 
the  branches  of  the  profunda  femoris  artery,  and  finally 
empties  into  the  femoral  vein  about  an  inch  and  a  half  below 
Poupart's  ligament.  In  its  course  the  vein  lies  at  the  inside 
and  in  front  of  the  profunda  artery.  (4)  The  long  or  in- 
ternal saphenous  vein.  This  large  subcutaneous  vein  emp- 
ties into  the  femoral  opposite  the  saphenous  opening.  See 
page  557.     The  femoral  vein  contains  several  valves. 

The  anterior  crural  nerve.     See  Lumbar  Plexus,  page  532. 

DISSECTION. 

Divide  the  iliotibial  band  just  below  the  tensor  muscle  and  turn  the  latter 
upward ;  at  the  same  time  look  for  its  nerve  supply. 

Divide  the  sartorius,  gracilis,  and  rectus  at  their  middle  and  reflect  their 
ends,  saving  their  nerves. 

Incise  the  fascia  stretching  across  the  front  of  Hunter's  canal,  and  expose 
the  femoral  artery,  vein,  and  internal  saphenous  nerve. 

Divide  the  adductor  longus  at  its  middle  and  lower  thirds  (below  where 
the  nerve  enters  it).  Draw  the  pectineus  upward,  dividing  it  through  the 
middle  if  necessary.  Cut  through  the  iliacus  under  Poupart's  ligament  and 
turn  the  lower  part  downward.  Divide  the  femoral  artery  below  the  origin 
of  the  profunda. 


THE  LOWER  EXTREMITY,  AXTERIOR.  575 

Hunter's  Canal.      Figs.  119,1 20. 

This  so-called  canal  is  no  "  canal  "  at  all  until  its  contents 
are  removed.  It  may  be  described  as  the  angular  space 
between  the  insertions  of  the  vastus  internus  on  the  outside 
and  the  adductor  longus  and  magnus  muscles  on  the  inside, 
and  reaching  from  the  opening  of  the  adductor  magnus 
upward  to  the  apex  of  Scarpa's  triangle.  This  angular 
inter\'al  is  "roofed"  over  by  an  aponeurotic  membrane 
extending  between  the  vastus  internus  and  the  adductor 
longus  and  magnus  muscles,  and  through  it  passes  the 
femoral  arter}^  vein,  and  long  saphenous  nerve,  the  situation 
of  these  structures  being  from  before  backward,  nerve, 
artery,  and  vein. 

Vastus  Externus.      Figs.  118,  121. 

Origin. — From  the  upper  half  of  the  anterior  intertro- 
chanteric line,  from  the  front  of  the  great  trochanter,  from 
the  horizontal  line  which  marks  the  base  of  the  great  tro- 
chanter, from  the  outer  part  of  the  gluteal  ridge  (insertion 
of  the  gluteus  maximus),  from  the  whole  length  of  the  outer 
lip  of  the  linea  aspera. 

Insertion. — Into  the  upper  and  outer  margins  of  the 
patella,  and  by  a  strong  aponeurosis  into  the  external  tuber- 
osity of  the  tibia  and  the  deep  fascia  of  the  leg. 

Nen>e  Supply. — The  anterior  crural. 

Action. — To  extend  the  leg,  the  outward  pull  of  the 
muscle  owing  to  the  obliquity  of  its  lower  fibres,  resists  a 
corresponding  internal  traction  of  the  vastus  internus. 

Vastus  Internus  and  Crureus.     Figs.  117,  119,  1 20. 

Origin. — From  the  front  and  sides  of  the  femur  for  its 
upper  two-thirds  (crureus  portion),  from  the  lower  half  of 
the  anterior  intertrochanteric  line,  and  its  continuation 
(spiral   line)  to  the  linea  aspera,  from  the  whole  length  of 


576  A  MANUAL   OF  ANATOMY. 

the  inner  up  of  the  linea  aspera,  from  the  internal  intermus- 
cular septum  and  the  tendon  of  the  adductor  magnus  (vas- 
tus portion). 

Insertion. —  Into  the  upper  border  of  the  patella  behind 
the  rectus  femoris  tendon  (the  crureus  portion),  into  the 
inner  margin  of  the  patella,  and  by  an  aponeurotic  expan- 
sion into  the  internal  tuberosity  of  the  tibia  and  the  deep 
fascia  of  the  leg  (vastus  portion). 

Ne7^ve  Supply. — The  anterior  crural. 

Action. — To  extend  the  leg  ;  the  vastus  internus  through 
its  lower  fibres  resists  the  outward  pull  of  the  vastus  ex- 
ternus. 

The  Lig-amentum  Patellae. 

This  is  the  continuation  of  the  tendons  of  the  four 
muscles  described  as  attached  to  the  patella,  namely  the 
rectus  femoris,  the  vastus  externus,  the  vastus  internus  and 
crureus,  which  having,  in  common,  the  action  of  extension 
of  the  leg  are  known  as  the  quadriceps  extensor  femoris. 
The  ligamentum  patellae  extends  from  the  apex  and  lower 
margins  of  the  patella  to  the  lower  portion  of  the  tibial 
tubercle.  It  is  about  an  inch  wide  above,  and  three-fourths 
of  an  inch  below,  one-fourth  of  an  inch  thick,  and  from  two 
to  three  inches  in  length. 

The  patella  should  be  regarded  as  a  sesamoid  bone 
developed  within  the  tendon  of  the  quadriceps  extensor  ;  its 
presence  renders  the  action  of  those  muscles  much  more 
effective  than  they  would  be  without  it. 

Adductor  Brevis.     Figs.  119,  120. 

Origin. — From  the  front  of  the  body  and  descending 
ramus  of  the  pubes  below  the  adductor  longus  and  between, 
the  gracilis  and  the  obturator  externus. 


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578  A  MAXUAL   OF  ANA  TOMY. 

Insertioji. — At  the  upper  third  of  the  shaft  of  the  femur, 
into  the  inner  lip  of  the  linea  aspera  and  the  hne  extending 
upward  to  the  lesser  trochanter. 

Nei've  Supply. — From  the  anterior  division  of  the  obtu- 
rator nerve. 

Action. — To  adduct  and  rotate  the  thigh  outward  ;  also, 
a  slight  flexor  of  the  thigh. 

Adductor  Mag-nus.     Figs.  119,  120. 

Origin. — From  the  front  of  the  rami  of  the  pubes  and 
ischium,  and  from  the  lower  part  of  the  tuberosity  of  the 
ischium. 

Insertion. — Into  the  back  of  the  femur  internal  to  the 
insertion  of  the  g-luteus  maximus,  along;  the  whole  length 
of  the  linea  aspera  betAveen  the  adductor  brevis,  adductor 
longus,  and  vastus  internus  on  the  inside,  and  the  short 
head  of  the  biceps  on  the  outside,  into  the  internal  condy- 
loid ridge  and  ending  in  a  strong  tendon,  which  is  attached 
to  the  adductor  tubercle  on  the  internal  condyle  of  the  femur. 

Nerve  Supply. — The  obturator  through  its  posterior  divi- 
sion, and  the  great  sciatic  which  gives  a  branch  to  the  pos- 
terior surface  of  the  muscle. 

Action. — To  adduct  the  thigh,  to  rotate  it  outward  (the 
upper  part  of  the  muscle) ;  and  to  extend  the  thigh 
(through  the  fibres  arising  from  the  ischial  tuberosity). 

The  femoral  opening  in  the  adductor  magnus  muscle. — 
This  is  a  gap  that  is  left  along  the  insertion  of  the  muscle 
at  the  middle  and  lower  thirds  of  the  thigh  through  which 
the  femoral  artery  and  vein  pass  to  enter  the  popliteal  space. 

Besides  the  opening  for  the  femoral  artery  and  vein  the 
adductor  magnus  muscle  is  perforated  along  its  insertion 
close  to  the  bone  by  the  branches  (three)  of  the  profunda 
which  pass  to  the  back  of  the  thigh. 


THE  LOWER  EXTREMITY,  ANTERIOR.  579 

The  Deep  Femoral — Profunda  Femoris.  Figs.  117,  118, 
1 19,  120. 

This  is  the  largest  and  most  important  branch  of  the 
femoral.  It  arises  from  the  outer  and  back  part  of  the 
femoral  at  a  point  varying  from  one  to  two  inches  from 
Poupart's  ligament,  the  average  distance  being  about  one 
and  one-half  inches.  Its  course  is  downward  and  inward 
behind  the  femoral  artery  and  vein,  then  behind  the  ad- 
ductor longus  muscle,  behind  which  it  continues  to  just 
above  the  femoral  opening  in  the  adductor  magnus,  when 
it  perforates  the  latter  close  to  its  insertion  and  enters  the 
popliteal  region  as  the  last  perforating  artery. 

In  its  course  it  lies  upon  the  iliacus,  pectineus,  adductor 
brevis  and  magnus  muscles.  The  vastus  internus  is  at  the 
outer  side  of  the  artery. 

TJic  Branches  of  the  Profunda. 

(i)  The  External  Circumflex. — It  arises  from  the 
outer  side  of  the  profunda  near  the  latter' s  origin.  It 
passes  outward  under  the  sartorius  and  rectus  femoris 
muscles,  interlacing  with  the  branches  of  the  anterior  crural 
nerve,  and  at  the  outer  side  of  the  thigh  divides  into  the 
ascending,  transverse,  and  descending  branches.  (a)  The 
ascending  brancli  (or  branches)  takes  an  upward  course  in 
the  interval  between  the  tensor  vaginae  femoris,  sartorius, 
rectus  femoris,  gluteus  medius  and  minimus,  and  iliacus 
muscles.  It  supplies  all  these  muscles,  also,  the  hip  joint, 
and  anastomoses  with  branches  from  the  superior  gluteal 
and  deep  circumflex  iliac  arteries.  if))  The  transverse 
brancli  (one  to  three)  winds  outward  around  the  femur, 
under  the  vastus  externus,  to  anastomose  at  the  back  of 
the  thigh  with  the  first  perforating  of  the  profunda,  the 
sciatic,  and  internal  circumflex  arteries.  (See  page  614.) 
if)  Descending  branches :    These  are  large  ones  \\-hich  turn 


580  A  MANUAL   OF  ANATOMY. 

downward  to  supply  the  front  and  outer  side  of  the  muscles 
of  the  thigh.  A  long  branch  reaches  to  the  outer  side  of 
the  knee  and  anastomoses  with  the  superior  external 
articular  branch  from  the  popliteal.  Other  branches  in 
front  extend  to  the  knee  joint  and  at  the  inner  side  anasto- 
mose with  the  deep  branch  of  the  anastomotica  magna. 

(2)  The  Internal  Circumflex  arises  from  the  inner  and 
back  part  of  the  profunda  artery  near  its  origin.  It  passes 
backward  between  the  tendon  of  the  psoas  and  pectineus, 
then  between  the  adductor  brevis  and  the  obturator  ex- 
ternus,  and  continues  between  the  quadratus  femoris  and 
the  adductor  magnus  to  the  back  of  the  thigh,  where  it 
anastomoses  with  the  sciatic,  external  cutaneous,  and  the 
first  perforating  artery  of  the  profunda,  thus  forming  the 
"crucial  anastomosis."  In  its  course  the  internal  circum- 
flex supplies  the  muscles  adjacent  to  it,  the  hip  joint, 
anastomoses  with  the  obturator  artery,  and  gives  off  a 
branch  of  considerable  size  which  follows  the  tendon  of 
the  obturator  externus  muscle  to  the  back  of  the  hip  joint 
(above  and  behind  the  quadratus  femoris)  to  anastomose 
with  the  sciatic,  and  gluteal  arteries. 

(3)  The  Perforating-  Arteries. — There  are  three  of  these 
given  off  from  the  profunda,  and  counting  the  termination 
of  that  vessel  itself,  makes  four.  The  three  perforating 
are  branches  from  the  profunda  as  it  lies  behind  the  ad- 
ductor longus  muscle.  They  all  pass  through  the  adductor 
magnus  (the  two  upper  ones  in  addition  piercing  the  ad- 
ductor brevis)  by  means  of  aponeurotic  openings  close  to 
the  bone,  and  appear  upon  the  back  of  the  adductor  mag- 
nus where  they  form  a  chain  of  anastomoses  with  each 
other.  In  addition  the  first  artery  anastomoses  wdth  the 
sciatic,  internal  circumflex  and  the  external  circumflex,  the 
third  perforating   with    the  termination   of   the  profunda. 


582  A  MANUAL  OF  ANATOMY. 

which  is  called  the  fourth  perforating  artery.  It  passes 
through  a  similar  gap  in  the  adductor  magnus  close  to  its 
insertion  and  just  above  the  opening  for  the  femoral  artery, 
to  the  back  of  the  adductor  magnus,  where  it  forms  an 
anastomosis  with  the  third  perforating,  and  the  superior 
muscular  and  articular  branches  of  the  popliteal.  All  the 
perforating  arteries  supply  the  muscles  near  them, 

Subcrureus. 

The  innermost  fibres  of  the  crureus  which  pass  to  the 
synovial  membrane  of  the  knee  joint.  Its  function  is  to 
keep  the  synovial  membrane   raised  up   out  of  the  way  of 

the  patella. 

Obturator  Externus.     Fig.  120. 

Origin. — From  the  inner  portion  of  the  external  surface 
of  the  obturator  membrane,  and  from  the  adjacent  portions 
of  the  rami  of  the  pubes  and  ischium. 

Insertion. — Into  the  digital  fossa  of  the  great  trochanter. 

Nerve  Supply. — Posterior  division  of  the  obturator  nerve. 

Action. — To  adduct  the  thigh,  to  rotate  the  thigh  out- 
ward, to  flex  the  thigh.  This  is  the  muscle  which  should 
have  been  called  the  "  sartorius  "  as  it  is  the  muscle  which 
crosses  the  legs. 

The  Obturator  Nerve.      Figs.  119,  120. 

For  its  formation,  and  course  through  the  pelvis,  see 
page  534- 

The  nerve  emerges  into  the  thigh  through  the  obturator 
gap  in  the  obturator  membrane  along  with  the  obturator 
artery.  It  divides  into  two  branches,  an  anterior  and  a 
posterior.  The  antcj'ior  branch  passes  over  the  upper  mar- 
gin of  the  obturator  externus,  over  the  adductor  brevis, 
and   under  the   pectineus   and    adductor   longus    muscles. 


THE  LOWER  EXTREMITY,  ANTERIOR.  583 

The  anterior  branch  supphes  the  pectineus,  adductor  brevis 
and  longus,  and  the  gracilis  muscles,  the  hip  joint,  and 
the  integument  at  the  middle  of  the  inner  side  of  the 
thigh. 

The  posterior  brancli  descends  through  the  obturator  ex- 
ternus  muscle,  then  between  the  adductor  brevis  and  mag- 
nus,  and  is  continued  as  a  long,  slender  filament  through 
the  lower  part  of  the  last  muscle  into  the  popliteal  space, 
through  which  it  descends  on  the  anterior  surface  of  the 
popliteal  vessels  to  the  posterior  ligament  of  the  knee 
joint. 

The  posterior  branch  supplies  the  obturator  externus, 
and  adductor  magnus  muscles,  the  hip  and  knee  joints. 

The  Accessory  Obturator  Nerve.      Fig.  107. 

For  the  formation,  course,  and  distribution  of  this  nerve, 
see  page  536. 

The  Obturator  Artery.      Figs.  112,  114,  120. 

This  is  a  branch  from  the  anterior  division  of  the  inter- 
nal iliac  artery.  For  its  course  and  branches  within  the 
pelvis,  see  page  547. 

The  artery  appears  with  the  nerve  at  the  upper  margin 
of  the  obturator  externus  muscle,  which  it  perforates,  and 
divides  into  an  internal  and  an  external  branch.  These 
course  along  the  internal  and  external  margins  of  the 
obturator  foramen  respectively,  anastomose  with  each  other 
at  the  lower  border  of  the  foramen  and  supply  branches  to 
the  adjacent  muscles.  In  addition  the  internal  branch 
anastomoses  with  the  internal  circumflex,  and  the  external 
branch  passes  outward  below  the  hip  (which  it  supplies) 
and  terminates  in  small  branches  which  anastomose  with 
the  terminal  branches  of  the  sciatic  artery. 


584  A  MANUAL   OF  ANATOMY. 

DISSECTION. 
Incisiojzs. — (i)  Continue  the  incision  down  the  front  of  the  leg  and  foot 
to  toes. 

(2)  Make  liberating  tiansverse  cuts  at  the  ankle  and  one  across  the  base 
of  the  toes. 

(3)  Carry  incisions  along  the  top  of  the  toes. 
Remove  the  integument  from  the  leg,  foot,  and  toes. 

Leave  the  superficial  veins  and  nerves  lying  upon  the  deep  fascia.  In 
removing  the  skin  from  the  toes  look  out  for  and  save  the  digital  nerves. 

The  Superficial  Fascia. 

The  superficial  fascia  of  the  leg  and  foot  is  continuous 
with  that  of  the  thigh.  It  varies  in  thickness  but  is  always 
thin  over  the  antero-internal  surface  of  the  tibia,  the  mal- 
leoli, and  the  dorsum  of  the  foot. 

The  Deep  Fascia.     Fig.  122. 

The  deep  fascia  continues  the  fascia  lata  from  the  thigh, 
being  directly  continuous  with  it  in  the  popliteal  space  and 
indirectly  about  the  front  of  the  knee  where  the  deep 
plane  of  fascia  is  attached  to  the  tuberosities  of  the  tibia 
and  the  head  of  the  fibula. 

In  front,  the  fascia  is  continuous  with  the  periosteum 
along  the  margins  of  the  antero-internal  surface  of  the 
tibia.  At  the  outer  side  of  the  leg,  the  fascia  is  fastened 
to  the  fibula  by  two  intermuscular  septa  which  enclose  the 
peroneus  longus  and  brevis.  At  the  ankle,  the  deep  fascia 
is  firmly  attached  to  the  bony  points  about  the  joint  and 
passes  into  the  deep  fascia  covering  the  dorsum  and  sole 
of  the  foot.  In  the  popliteal  space  and  about  the  ankle, 
the  fascia  is  reinforced  by  transverse  fibres  to  which,  in  the 
latter  instance,  the  names  of  annular  ligaments  are  given. 

The  Anterior  Annular  Ligament.      Fig.  123. 

(i)  The  upper  portion  :  This  is  a  band  about  two  inches 


THE  LOWER  EXTREMITY,  AXTERIOR.  585 

wide  that  passes  from  the  front  of  the  tibia  to  the  front  of 
the  fibula  just  above  the  ankle  joint.  It  contains  one  syno- 
vial sheath  for  the  tendon  of  the  tibialis  anticus.  The  ten- 
dons of  the  other  muscles  pass  under  it  without  any  synovial 
investment. 

(2)  The  lower  portion.  This  band  lies  just  below  the 
level  of  the  joint,  and  is  arranged  like  a  "  horizontal  "  -< . 
The  single  limb  being  external  and  attached  to  the  upper 
anterior  surface  of  the  calcis. 

The  single  limb  is  split  for  the  passage  of  the  tendons  of 
the  extensor  longus  digitorum  and  the  peroneus  tertius, 
and  is  lined  by  synovial  membrane  common  for  these 
tendons. 

The  upper  "  leg"  of  the  -<  is  attached  to  the  internal 
malleolus,  passing  over  the  tendon  of  the  extensor  proprius 
hallucis  and  mostly  under  the  tendon  of  the  tibialis  anticus, 
a  thin  investment  covering  the  tendon  of  the  latter  muscle. 

The  tendon  of  the  former  muscle  has  a  separate  synovial 
sheath  under  this  portion  of  the  ligament.  The  lower 
"  leg"  of  the  -<  passes  over  the  tendons  of  the  extensor 
proprius  hallucis  and  tibialis  anticus  to  the  inner  side  of  the 
foot  where  it  blends  with  the  plantar  fascia. 

The  synovial  sheath  of  the  tibialis  anticus  is  prolonged 
from  the  upper  portion,  down  under  this  part  of  the  annular 
ligament. 

The  External  Annular  Ligament,     Fig.  123. 

This  is  that  portion  of  the  deep  fascia  of  the  leg  and 
foot,  which  extends  from  the  external  malleolus  to  the  outer 
posterior  and  lower  borders  of  the  os  calcis.  It  retains 
the  tendons  of  the  peroneus  longus  and  brevis  in  place 
behind  the  external  malleolus.  The  tendons  are  surrounded 
by  a  common  synovial  sheath. 


586  A  MANUAL   OF  ANATOMY. 

The  Internal  Annular  Ligament.      Fig,  131. 

This  is  the  portion  of  the  deep  fascia  reaching  from  the 
internal  malleolus  to  the  inner  lower  and  posterior  borders 
of  the  OS  calcis. 

For  the  relations  of  the  important  structures  which  pass 
under  this  ligament,  see  page  632. 

The  External  (Short)  Saphenous  Vein. 

This  begins  at  the  outer  side  of  the  venous  plexus  found 
upon  the  dorsum  of  the  foot.  It  passes  backward  along 
the  outer  margin  of  the  foot,  below  the  external  malleolus, 
then  upward  over  the  back  of  the  leg,  perforates  the  deep 
fascia  of  the  leg  at  the  lower  part  of  the  popliteal  space  and 
empties  into  the  popliteal  vein. 

(For  the  dissection  of  the  vein  at  the  back  of  the  leg, 
see  page  618.) 

The  vein  receives  its  tributaries  from  the  outer  side  of 
the  foot,  outer  and  back  parts  of  the  leg,  and  a  large  vein 
from  the  lower  part  of  the  thigh  just  before  it  perforates 
the  deep  fascia. 

The  Internal  (Long)  Saphenous  Vein. 

This  emerges  from  the  inner  side  of  the  dorsal  venous 
arch  of  the  foot.  Its  course  is  upward  in  front  of  the  inter- 
nal malleolus,  along  the  antero-internal  border  of  the  leg 
to  the  inner  side  of  the  knee,  where  it  lies  behind  the  inter- 
nal condyle  of  the  femur.  Its  further  course  and  tribu- 
taries are  given  on  page  557. 

The  internal  saphenous  receives  the  subcutaneous  veins 
from  the  inner  side  of  the  foot  and  leg. 

Both  saphenous  veins  communicate  with  the  venae  com- 
ites  of  the  deep  parts  of  the  leg  by  veins  which  perforate 
the  deep  fascia  at  irregular  intervals.     They  also  communi- 


Fig.  122.  Dissection  of  Leg,  Anterolateral  Region— i,  Deep  fascia.  2, 
Musculocutaneous  nerve.  3,  Short  or  e.xternal  saphenous  nerve.  4.  Internal  branch 
of  anterior  tibial. 


588  A  MANUAL   OF  ANATOMY. 

cate  with  each  other  at  variable  points.     They  both  have 
numerous  valves. 

The  Internal  (Long)  Saphenous  Nerve.     See  page  566. 
The  cutaneous  branches  of  the  external  popliteal  nerve 
are  two  small  nerves  which  supply  the  superficial  region  of 
the  upper  and  outer  thirds  of  the  leg. 

The  Musculocutaneous  Nerve.     Fig.  122. 

This  is  one  of  the  terminal  branches  of  the  external  pop- 
liteal nerve  just  after  it  has  turned  around  the  neck  of  the 
fibula,  the  other  being  the  anterior  tibial. 

The  musculocutaneous  nerve  descends  between  the  pero- 
neus  longus  and  brevis,  which  it  supplies,  pierces  the  deep 
fascia  at  the  outer  side  of  the  leg  at  its  lower  and  middle 
thirds,  and  is  distributed  to  the  integument  covering  the 
outer  and  front  of  the  lower  third  of  the  leg,  the  dorsum 
of  the  foot,  the  front  and  inner  side  of  the  great  toe,  the 
contiguous  sides  of  the  second  and  third,  third  and  fourth, 
and  fourth  and  fifth  toes.  The  opposite  sides  of  the  first  and 
second  toes  are  supplied  by  the  termination  of  the  anterior 
tibial  nerve,  and  the  outer  side  of  the  little  toe  and  foot 
receives  its  innervation  from  the  external  saphenous  nerve. 
Both  of  these  nerves  receive  a  filament  from  the  musculo- 
cutaneous. 

The   External   or   Short   Saphenous  Nerve. — See  page 
616. 

DISSECTION. 

Remove  the  deep  fascia,  leaving  the  annular  ligaments  in  place. 

Clean  all  the  muscles,  vessels,  and  nerves  upon  the  front  of  the  leg  and 
foot  as  far  as  possible  without  dividing  any. 

At  the  last,  after  the  relations  of  parts  are  fully  seen,  then  remove  the  ante- 
rior annular  ligaments,  and  the  extensor  brevis  digitorum,  and  complete  the 
foot. 


THE  LOWER  EXTREMITY,  ANTERIOR.  589 

Tibialis  Anticus.      Figs.  123,  124, 

Origin. — From  the  under  surface  of  the  external  tuber- 
osity of  the  tibia,  from  the  upper  half  or  two-thirds  of  the 
outer  surface  of  the  tibia,  from  the  adjacent  portion  of  the 
interosseous  membrane,  from  the  upper  third  of  the  inner 
surface  of  the  deep  fascia  covering  the  muscle,  and  from 
the  intermuscular  septum  between  the  extensor  longus  digi- 
torum  and  itself. 

Insertion. — Into  the  adjoining  portions  of  the  inner  and 
lower  surfaces  of  the  internal  cuneiform  and  first  metatarsal 
bones. 

Nerz'e  Supply. — The  anterior  tibial  branch  of  the  external 
popliteal  nerve. 

Action. — To  flex  the  foot  upon  the  leg,  to  raise  (invert) 
the  inner  border  of  the  foot,  to  adduct  the  anterior  part  of 
the  foot. 

Extensor  Longus  Digitorum.      Figs.  123,  124, 

Origin. — From  the  external  tuberosity  of  the  tibia,  from 
the  front  of  the  head  of  the  fibula,  from  the  upper  three- 
fourths  of  the  anterior  surface  of  the  fibula,  from  the  upper 
third  of  the  interosseous  membrane,  and  for  the  same  extent 
from  the  inner  surface  of  the  deep  fascia  covering  the  leg, 
and  from  the  intermuscular  septa  between  it  and  the  border- 
ing muscles. 

Insertion. — Into  the  four  outer  toes  by  separate  tendons 
which  divide  into  three  slips.  The  middle  slip  in  each  case 
being  inserted  into  the  base  of  the  second  phalanx,  the 
other  two  tendons  passing  around  the  middle  one  to  be  in- 
serted into  the  bases  of  the  third  phalanx. 

From  the  margins  of  each  tendon  slips  pass  to  the  lateral 
ligaments  of  the  metacarpophalangeal  articulations. 

The  tendons  of  the  interossei,  lumbricales,  and  extensor 


590  A  MANUAL  OF  ANATOMY. 

brevis  digitorum  muscles  blend  with  the  margins  of  the 
long  extensor  tendons  along  the  first  phalanges. 

Nerve  Supply. — The  anterior  tibial. 

Action. — To  extend  the  toes,  to  flex  the  foot  upon  the 
leg.  The  action  upon  the  toes  is  most  marked  upon  the 
first  phalanges,  the  extension  of  the  second  and  third 
phalanges  being  effected  through  the  interossei  and  lumbri- 
cales. 

Extensor  Proprius  Hallucis.     Figs.  123,  124. 

Origin. — From  the  middle  two-fourths  of  the  anterior 
surface  (antero-internal)  of  the  fibula  and  from  the  interos- 
seous membrane  adjacent  to  this  origin. 

Insertion. — Into  the  dorsal  surface  of  the  base  of  the  last 
phalanx  of  the  great  toe.  At  the  metatarsophalangeal 
articulation  a  fibrous  expansion  from  the  tendon  passes  to 
the  lateral  ligaments  of  the  articulation. 

Nerve  Supply. — The  anterior  tibial. 

Action. — To  extend  the  great  toe,  to  flex  the  foot,  to 
adduct  the  fore  part  of  the  foot,  to  raise  (invert)  the  inner 
border  of  the  foot.  Due  to  the  tendon  being  crossed  by 
the  lower  leg  of  the  -<  ligament. 

See  Attachments  of  Annular  Ligament,  page  585. 

Peroneus  Tertius.     Figs.  123,  124. 

Origin. — From  the  lower  fourth  of  the  anterior  surface 
of  the  fibula,  being  continuous  with  the  extensor  longus 
digitorum,  from  the  adjacent  interosseous  membrane,  and 
intermuscular  fascia. 

hisertion. — Into  the  upper  surface  of  the  base  of  the  fifth 
metatarsal  bone. 

Nerve  Supply. — The  anterior  tibial. 

Action. — To  flex  the  ankle-joint,  to  raise  the  outer  border 
of  the  foot  (e version),  to  abduct  the  fore  part  of  the  foot. 


592  A  MANUAL   OF  ANATOMY. 

Extensor  Brevis  Digitorum.      Fig.  124. 

Origin. — From  the  outer  and  upper  surface  of  the  fore 
part  of  the  os  calcis,  from  the  external  calcaneo-astragaloid 
ligament,  and  from  the  lower  band  of  the  anterior  annular 
ligament. 

Insertion. — By  four  tendons.  The  first  tendon  is  inserted 
into  the  outer  surface  of  the  base  of  the  first  phalanx  of  the 
great  toe  ;  the  rest  of  the  tendons  merge  into  the  outer 
margins  of  the  tendons  of  the  extensor  longus  digitorum 
(just  over  the  bases  of  the  first  phalanges),  and  by  them 
are  attached  to  the  second  and  third  phalanges. 

Nerve  Supply. — The  anterior  tibial. 

Action. — To  extend  and  adduct  (toward  the  middle  line 
of  the  second  toe)  the  first  phalanx  of  the  great  toe,  to  ex- 
tend the  third,  second,  and  first  phalanges  of  the  next  three 
toes.  The  action  of  the  muscle  upon  the  toes  is  more  upon 
the  distal  than  the  proximal  segments  of  them. 

Dorsal   Interossei.      Fig.  125. 

There  are  four  dorsal  interossei  muscles.  There  is  one 
on  either  side  of  the  second  toe  ;  then  the  third  and  fourth 
toes  have  each  a  muscle  upon  their  outer  (fibular)  side. 

Origin. — From  the  adjacent  sides  of  the  metatarsal  bones 
between  which  they  lie.  Between  the  two  heads  pass  the 
posterior  perforating  arteries.  (In  the  case  of  the  first  mus- 
cle it  is  the  communicating  artery.) 

Insertion. — Into  the  bases  of  the  first  phalanges,  and  into 
the  lateral  margins  of  the  tendons  of  the  extensor  longus 
digitorum  ;  upon  the  inner  side  of  the  second  toe  for  the 
first  muscle,  and  upon  the  outer  side  of  the  second,  third, 
and  fourth  toes  for  the  remaining  muscles. 

Nerve  Supply. — The  external  plantar  branch  of  the  pos- 
terior tibial  nerve. 


THE  LOWER  EXTREMITY,  ANTERIOR.  593 

Action. — Same  as  in  the  hand  {q.v.,  page  389),  to  flex 
the  first  set  of  phalanges,  to  extend  the  second  and  third 
sets  of  phalanges,  to  abduct  the  toes  from  the  middle  line 
drawn  through  the  second  toe. 

The  Anterior  Tibial  Artery.      Figs.  124,  225. 

This  artery  is  the  anterior  branch  of  bifurcation  of  the 
popliteal,  just  at  the  lower  border  of  the  popliteus  muscle. 
See  page  623.  The  course  of  the  anterior  tibial  artery  is 
forward  between  the  two  heads  of  the  tibialis  posticus 
muscle,  then  between  the  tibia  and  fibula,  where  the  artery 
crosses  over  the  top  of  the  interosseous  membrane  to  gain 
the  front  of  the  leg. 

It  turns  downward  resting  upon  the  interosseous  mem- 
brane and  between  the  tibialis  anticus  and  the  extensor 
longus  digitorum  for  the  upper  third  of  its  course,  then 
between  the  tibialis  anticus  and  the  extensor  proprius  hallu- 
cis  for  the  middle  third,  then  finally  between  the  tendon 
of  the  extensor  proprius  hallucis  and  the  tibia  for  the 
lower  third.  In  front  of  the  ankle  joint  the  name  of  the 
artery  is  changed  to  the  dorsalis  pedis.  The  artery  has  on 
either  side  an  accompanying  vein  which  frequently  commu- 
nicate with  each  other.  The  anterior  tibial  nerve  lies  at  the 
outer  side  of  the  artery  for  its  upper  third,  over  the  front 
of  the  artery  for  its  middle  third,  and  then  again  at  the  outer 
side  of  the  artery  for  the  lower  third. 

The  course  of  the  artery  is  indicated  upon  the  outer 
surface  of  the  leg  by  a  line  drawn  from  the  inner 
margin  of  the  head  of  the  fibula  to  the  mid-point  in  front 
of  the  ankle  joint  between  the  malleoli.  The  deeper 
guide  to  the  artery  is  the  intermuscular  space  at  the  outer 
margin  of  the  tibialis  anticus  muscle,  for  the  upper  two- 
thirds  ;  and  between  the  tendons  of  the  extensor  proprius 
38 


594  A  MANUAL   OF  ANA  TOMY. 

hallucis  and  the  tibialis  anticus  for  the  lower  third  of  the 
leg. 

TJie  Branches  of  the  Anterior  Tibial. 

(i)  The  posterior  tibial  recurrent.  This  is  found  when 
dissecting  the  back  of  the  leg.  It  runs  upward  between 
the  popliteus  muscle  and  the  posterior  ligament  of  the  knee 
joint.     It  is  a  small  branch  and  often  wanting. 

(2)  The  anterior  tibial  recurrent.  This  is  a  branch  of 
considerable  size  that  runs  upward  through  the  origin  of 
the  tibialis  anticus  close  to  the  bone,  and  supplies  the  outer 
side  of  the  front  of  the  knee,  anastomosing  with  the  ex- 
ternal inferior  and  superior  articular  from  the  popliteal  and 
the  long  articular  branch  of  the  external  circumflex  to  the 
outer  side  of  the  knee. 

(3)  The  muscular  branches  are  numerous  and  supply  the 
muscles  bordering  upon  the  artery. 

(4)  The  malleolar.  The  external  is  slightly  larger  than 
the  internal.  They  pass  to  the  external  and  internal  mal- 
leolar regions,  which  they  supply  ;  in  their  course  they  run 
beneath  the  tendons  of  the  muscles  at  either  side  of  the 
anterior  tibial  artery.  The  internal  malleolar  forms  an  an- 
astomosis with  the  posterior  tibial,  internal  plantar,  and 
the  internal  calcanean  ;  the  external,  with  the  anterior  pe- 
roneal, the  external  plantar,  and  the  tarsal  branch  of  the 
dorsalis  pedis. 

The  Anterior  Peroneal.     See  page  633.      Fig.  125. 

It  is  found  as  it  appears  through  the  interosseous  mem- 
brane, between  the  tibia  and  the  fibula,  about  two  or  three 
inches  above  the  ankle  joint.  It  passes  downward  between 
the  two  bones  of  the  leg  to  the  front  of  the  outer  side  of 
the  ankle,  which  it  supplies,  and  where  it  enters  into  an 
anastomosis  with  the  external  malleolar  artery. 


THE  LOWER  EXTREMITY,  ANTERIOR.  595 

The  Dorsalis  Pedis  Artery.      Fig.  125. 

This  is  the  continuation  of  the  anterior  tibial  from  the 
front  of  the  ankle,  along  the  front  of  the  foot,  to  the  space 
between  the  first  and  second  metatarsal  bones,  where  it  ter- 
minates by  dividing  into  the  dorsalis  hallucis  and  the  deep 
communicating  artery. 

In  its  course  it  passes  between  the  tendons  of  the  exten- 
sor proprius  hallucis  and  the  extensor  longus  digitorum, 
and  is  crossed  near  its  termination  by  the  inner  tendon  of 
the  extensor  brevis  digitorum. 

The  venae  comites  lie  upon  either  side  of  the  artery,  and 
the  anterior  tibial  nerve  at  its  outer  side. 

The  course  of  the  dorsalis  pedis  is  indicated  by  a  line 
drawn  from  the  mid-point  between  the  malleoli  to  the  inter- 
val between  the  first  and  second  metatarsal  bones. 

Tlie  Branches  of  the  Dorsalis  Pedis. 

(i)  The  internal  tarsal.  Several  small  branches  to  the 
inner  side  of  the  foot. 

(2)  The  external  tarsal  turns  outward  beneath  the  exten- 
sor brevis  digitorum  muscle  to  the  outer  side  of  the  foot, 
where  it  enters  into  an  anastomosis  with  the  external 
malleolar,  anterior  peroneal,  external  plantar,  and  the  meta- 
tarsal arteries. 

(3)  The  metatarsal  artery  passes  outward  under  the  ten- 
dons of  the  extensor  brevis  digitorum  muscle  and  across  the 
heads  of  the  four  outer  metatarsal  bones  to  the  outer  border 
of  the  foot. 

Above,  it  anastomoses  with  the  external  tarsal,  and  at  the 
outer  side  of  the  foot  with  the  external  plantar.  From  the 
front  part  of  the  artery  the  three  interosseous  branches  are 
given  off. 

The  interosseous  arteries  pass  forward  in  the  second, 


596  A  MANUAL  OF  ANA  TOMY. 

third,  and  fourth  spaces,  resting  upon  the  interosseous 
muscles.  At  their  beginning  they  communicate  with 
the  plantar  arch  by  means  of  the  posterior  perforating- 
branches,  and  at  the  metatarsophalangeal  articulations  they 
communicate  with  the  corresponding  plantar  digital  artery, 
through  the  anterior  perforating-  branches.  The  inter- 
osseous arteries  then  divide  into  the  dorsal  collateral  digi- 
tal vessels  which  supply  adjacent  sides  of  the  dorsal  surface 
of  the  four  outer  toes.  The  outer  side  of  the  fifth  toe  be- 
ing supplied  by  a  small  branch  from  the  fourth  dorsal  inter- 
osseous artery  just  before  it  bifurcates. 

The  Dorsalis  Hallucis  artery  is  the  continuation  of  the 
dorsalis  pedis  to  the  metatarsophalangeal  joint  where  it  di- 
vides into  two  collateral  digital  branches  to  the  adjacent  sides 
of  the  first  and  second  toes.  The  dorsalis  hallucis  commu- 
nicates just  before  its  division  with  the  corresponding  plan- 
tar digital  artery,  and  near  this  point  gives  off  the  dorsal 
collateral  digital  branch  to  the  inner  side  of  the  great  toe. 
This  last  branch  is  inconstant. 

The  Communicating  Artery.     Fig.  125. 

This  is  a  branch  of  bifurcation  of  the  dorsalis  pedis,  and 
corresponding  to  the  first  posterior  perforating  artery,  passes 
backward  through  the  interval  between  the  first  and  second 
metatarsal  bones  to  the  sole  pf  the  foot,  where  it  completes 
the  plantar  arch  by  anastomosing  with  the  external  plantar. 
It  then  continues  forward  as  the  fifth  plantar  digital  artery, 
between  the  first  and  second  toes,  receives  the  anterior  per- 
forating from  the  dorsalis  hallucis,  sends  a  branch  to  the 
plantar  surface  of  the  inner  side  of  the  great  toe,  and 
divides  into  the  collateral  digital  (plantar)  branches  for 
the  contiguous  sides  of  the  first  and  second  toes. 


Fig.  124.  Dissection  of  Leg,  Anterolateral  Region. — i,  Superior  external 
articular  artery.  2,  Ligamentum  patella.  3,  Tubercle  of  tibia.  4,  4,  Tibialis  anticus. 
5,  Anterior  tibial  artery  and  muscular  branches.  6,  Anterior  tibial  nerve.  7,  Tibia.  8, 
Articular  branch,  anastomosing  with  9,  Anterior  peroneal  and'  10,  The  external 
malleolar.  11,  Tarsal  artery.  12,  Dorsalis  pedis  73,  Metatarsal  artery.  14,  Semi- 
tendinosus.  15,  Tendon  of  biceps.  16,  External  popliteal  nerve.  17,  Extensor 
proprius  hallucis.  18,  Extensor  longus  digitorum.  19,  22,  Peroneus  longus.  20,  23, 
Peroneus  brevis.     21,  External  malleolus.     24,  Extensor  brevis  digitorum. 

Fig.  125.  Dissection  of  Foot,  Dorsal  Surface. —i,  i,  i,  Anterior  tibial  nerve. 
2,  2,  Anterior  tibial  artery.  3,  Internal  malleolar  artery.  4,  Internal  branch  of  ante- 
rior tibial  nerve.  5,  Internal  tarsal  artery.  6,  Dorsalis  pedis  artery.  7,  Communi- 
cating artery.  8,  Dorsalis  hallucis  artery.  9,  Anterior  peroneal  artery.  10,  Ex- 
ternal branch  of  anterior  tibial  nerve  traced  to  extensor  brevis  digitorum  which 
has  been  reflected.  11,  External  malleolar  artery.  12,  External  tarsal  arterj'.  13, 
Metatarsal  artery.     14,  The  four  dorsal  interossei. 


598  A  MANUAL  OF  ANATOMY. 

The  Anterior  Tibial  Nerve.     Figs.  124,  125, 

The  remaining  branch  of  division  of  the  external  popli- 
teal nerve,  the  other  being  the  musculocutaneous. 

The  anterior  tibial  nerve  descends  through  the  substance 
of  the  extensor  longus  digitorum  muscle,  keeps  at  the  outer 
side  of  the  anterior  tibial  artery  for  its  upper  third,  then 
runs  upon  the  anterior  surface  of  the  artery  in  its  middle 
third,  leaves  the  artery  in  its  lower  third,  remaining  at  its 
outer  side,  passes  with  the  long  tendons  under  the  two 
bands  of  the  anterior  annular  ligament,  and  terminates  here 
by  dividing  into  two  branches,  an  internal  and  external. 

The  internal  branch  continues  forward  along  the  outer 
side  of  the  dorsalis  pedis  artery  to  the  first  interosseous 
space,  receives  a  branch  from  the  musculocutaneous  and 
divides  into  collateral  digital  nerves  to  the  adjacent  sides 
of  the  great  and  second  toes.  The  external  branch  turns 
outward  under  the  extensor  brevis  digitorum,  becomes 
slightly  enlarged,  and  from  this  enlargement  filaments  pass 
to  the  muscles  and  tarsal  articulations. 

In  its  course  the  anterior  tibial  suppHes  muscular  branches 
to  the  extensor  longus  digitorum,  tibialis  anticus,  extensor 
proprius  hallucis,  peroneus  tertius,  and  the  extensor  brevis 
digitorum  ;  articular  branches  to  the  ankle  and  the  tarsal 
joints. 


THE  LOWER  EXTREMITY,  POSTERIOR.  599 

THE  LOWER  EXTREMITY,  Posterior. 

Landmarks.     Figs.  76,  126. 

The  landmarks  as  given  on  page  554  should  be  consulted. 

The  crest  of  the  ilium  cur\-es  backward  to  terminate  in 
the  posterior  superior  spinous  process  of  the  ilium.  The 
spines  of  the  sacrum  and  the  termination  of  the  spinal 
column  in  the  coccyx  are  easily  felt. 

The  tuberosity  of  the  ischium  is  an  important  reference 
point  to  which  the  posterior  part  of  Nelaton's  line  is  carried. 

The  difficulty  in  determining  what  is  the  most  prominent 
part  of  the  tuberosity  of  the  ischium  is  the  difficulty  be- 
longing to  all  so-called  anatomical  "points,"  which  are  in 
reality  "broad  surfaces."  This  difficulty  of  exactly  locat- 
ing these  various  "  points  "  becomes  increased  in  the  living, 
especially  if  there  is  a  thick  overlying  pad  of  fatty  tissue. 
The  student  must  be  cautioned  in  regard  to  such  "points" 
as  the  costal  cartilages,  tuberosity  of  the  ischium,  condyles 
and  tuberosities  of  the  various  long  bones.  Such  land- 
marks are  called  "  points  "  by  common  consent,  but  in 
reality  they  are  very  considerable  areas. 

The  bony  parts  about  the  popliteal  region  demand  atten- 
tion, and  the  ham-strings,  which  form  the  lateral  boundaries 
of  the  same.  They  are  rendered  prominent  by  extending 
the  leg.  The  tendo-Achillis  is  readily  appreciated,  espe- 
cially if  the  foot  is  flexed. 

DISSECTION. 
Incisions. — (l)  Continue  the  median  incision  of  the  trunk  to  the  tip  of  the 
coccyx. 

(2)  Make  a  transverse  cut  from  the  last  dorsal  vertebra  outward  (same  as 
3,  page  360). 

(3)  From  the  middle  of  the  sacrum  carry  a  curved  incision  outward  over 
the  crest  of  the  ilixmi  to  join  the  similar  anterior  one. 


600  A  MANUAL   OF  ANATOMY. 

Remove  the  integument  from  the  lumbar,  gluteal,  and  posterior  crural 
regions. 

To  expose  the  back  of  the  thigh  (and  for  that  matter  the  leg)  it  will  not  be 
necessary  to  make  median  and  transverse  incisions.  But  reflect  the  integu- 
ment from  the  outer  to  the  inner  side  of  the  limb,  and  from  above  downward, 
at  this  time  as  far  downward  as  the  calf  of  the  leg.  Do  not  cut  this  large 
skin  flap  away  but  use  it  for  covering  the  part. 

The  Superficial  Fascia,  Posterior  Portion. 

This  layer  is  continuous  with  the  fascia  described  upon 
the  anterior  aspect  of  the  thigh.     See  page  556. 

Upon  the  small  of  the  back  and  over  the  buttocks,  the 
superficial  fascia  is  usually  very  thick  and  consists  of  very 
coarse  granular  adipose  tissue.     See  page  360. 

DISSECTION. 
Remove  the  superficial  fascia  from  the  entire  area  corresponding  to  the 
integument,  saving  the  cutaneous  nerves  and  veins. 

The  Fascia  Lata,  Posterior  Portion. 

The  posterior  portion  of  the  fascia  is  continuous  with  the 
anterior  at  the  sides  of  the  thigh,  with  the  deep  fascia  of 
the  leg  in  the  popHteal  space,  and  is  attached  above  and 
below  and  at  the  sides,  as  given  on  page  558. 

Above,  the  fascia  divides  into  two  laminae  between  which 
the  gluteus  maximus  lies,  and  into  the  angle  of  division  at 
the  outer  side  of  the  thigh  it  is  inserted  similar  to  the  tensor 
vaginae  femoris.  The  external  lamina  is  the  stronger,  and 
is  attached  to  the  coccyx  and  the  sacrum.  The  internal 
layer  blends  with  the  outer  margin  of  the  great  sacrosciatic 
ligament.  The  two  layers  become  united  at  the  margins 
of  the  gluteus  maximus,  the  external  portion  then  passing 
over  the  gluteus  medius  and  being  fastened  to  the  crest  of 
the  ilium,  the  internal  to  the  tuberosity  of  the  ischium  and 
the  pubic  arch. 

The  portion  of  the  fascia  lata  into  which  the  gluteus 


Fig.  126.  Dissection  of  Gluteal  Region,  Back  of  Thigh  and  Knee. — i. 
Gluteal  maximus.  2,  Long  head  of  biceps.  3,  Great  sciatic  nerve.  4,  Short  head  of 
biceps.  5,  Internal  popliteal  nerve.  6,  External  popliteal  nerve.  7,  Posterior 
saphenous  artery  (cutaneous).  8,  Outer  head  of  gastrocnemius,  g,  Communicans 
tibialis  nerve.  10,  Communicans  fibularis  (peronei).  11,  Semimembranosus.  12, 
Semitendinosus.  13,  Perforating  artery.  14,  Muscular  branches  of  great  sciatic  to 
II  and  12.  15,  Fourth  perforating  artery.  16,  Popliteal  vein.  17,  Popliteal  artery. 
18,  Tendon  of  gracilis.  19,  Tendon  (divided)  of  Sartorius.  20,  Inner  head  of  gas- 
trocnemius. 21,  Great  sacrosciatic  ligament.  22,  Sciatic  artery.  23,  Small  sciatic 
nerve  and  branches.  24,  Tuberosity  of  ischium  25,  SeniiniembVanosus.  26,  Nerve 
1025.  27,  Adductor  magnus.  2S,  Perforating  artery.  29,  Popliteal  vein.  30,  Popli- 
teal artery.  31,  Superior  internal  articular  artery.  32,  Inferior  muscular  (sural) 
arteries.  33,  Inner  head  of  gastrocnemius.  34,  Internal  inferior  articular  artery. 
35,  Gluteus  medius.  36,  Gluteal  artery.  37,  Muscular  branches  (divided)  to  the  gluteus 
maximus  (removed).  38,  Pyriformis.  39,  Obturator  internus  and  gemelli.  40, 
Great  trochanter.  41,  Anastomotic  branch  of  sciatic  artery.  42,  Quadratus  femoris. 
43,  Insertion  of  gluteus  maximus.  44,  First  perforating  artery.  45,  Second  perforat- 
ing artery.  46,  Vastus  externus.  47,  Third  perforating  artery.  48,  Short  head  of 
biceps.  49,  Great  sciatic  nerve.  50,  Cut  end  of  long  head  of  biceps.  51,  External 
popliteal  nerve.  52,  Internal  popliteal  nerve.  53,  Superior  external  articular  artery. 
54,  Nerve  to  outer  head  (56)  of  gastrocnemius.  55,  Inferior  muscular  (sural)  arteries. 
56,  Outer  head  of  gastrocnemius.     57,  Plantaris. 


602  A  MANUAL  OF  ANA  TOMY. 

maximus  is  inserted  is  that  thickened  layer  already  de- 
scribed as  the  iliotibial  band,  see  page  558. 

In  the  popliteal  space  the  fascia  lata  is  much  increased  in 
strength  by  the  addition  of  transverse  fibres  which  bind 
together  the  sides  of  the  space.  The  external  or  short 
saphenous  vein  pierces  the  fascia  at  this  place. 

Upon  the  inner  portion  of  the  thigh  the  fascia  is  thinner 
than  elsewhere. 

The  Cutaneous  Nerves. 

These  are  the  terminal  filaments  of  the  last  dorsal  and 
the  posterior  branch  of  the  iliohypogastric  nerves  over  the 
upper  part  of  the  gluteal  region  and  the  great  trochanter  ; 
the  cutaneous  branches  of  the  sacral  nerves  over  the  inner 
portion  of  the  gluteal  region  ;  the  recurrent  branches  of  the 
small  sciatic  over  the  lower  portion  of  the  gluteus  maximus  ; 
branches  from  the  small  sciatic  down  the  back  of  the  thigh, 
and  popliteal  space  ;  and  the  posterior  branches  of  the  ex- 
ternal cutaneous  (see  page  561)  along  the  outer  side  of  the 

thigh. 

DISSECTION. 

Remove  the  fascia  lata  from  the  gluteus  maximus  muscle,  cutting  in  the 
direction  of  the  fibres  of  the  muscle.     Expose  the  muscle  entirely. 

Incise  the  fascia  in  the  middle  line  from  the  gluteus  maximus  to  below  the 
knee  and  remove  it  from  the  deeper  parts,  noting  the  compartments  for  the 
muscles.      Save  the  small  sciatic  nerve. 

Clean  the  muscles  of  the  buttocks,  thigh,  and  the  upper  part  of  the  popliteal 
space. 

Gluteus  Maximus.      Fig.  126. 

Origin. — From  the  crest  and  the  outer  surface  of  the 
ilium  posterior  to  the  superior  curved  line  thereof,  from 
the  lower  half  of  the  posterior  and  lateral  part  of  the 
sacrum,  from  the  side  of  the  coccyx,  from  the  lumbar 
aponeurosis  between  the  ilium  and  sacrum,  and  from  the 
posterior  surface  of  the  great  sacrosciatic  ligament. 


THE  LOWER  EXTREMITY,  POSTERIOR.  603 

Insertion. — Into  the  iliotibial  band  over  the  great  tro- 
chanter of  the  femur. .  Into  the  gluteal  (vertical)  ridge 
which  extends  from  the  posterior  surface  of  the  great  tro- 
chanter to  the  outer  bifurcation  of  the  linea  aspera.  A 
distance  of  about  two  inches. 

Nerve  Supply. — The  inferior  gluteal  branch  of  the  sacral 
plexus.  This  nerve  is  usually  included  within  the  sheath 
of  the  small  sciatic  and  consequently  is  said  to  be  a  branch 
of  that  nerve.      See  page  552. 

Action. — The  attachments  of  all  the  posterior  muscles 
of  the  thigh  should  be  very  carefully  determined,  then 
their  action  when  the  thigh  is  in  an  extended  position,  and 
finally  when  it  is  flexed  at  various  angles.  It  will  only  be 
by  such  careful  study  that  the  complex  actions  of  these 
gluteal  and  external  rotator  muscles  will  be  understood. 

To  attempt  to  commit  to  memory  the  action  of  muscles 
from  the  book  is  all  wrong,  unless  the  demonstration  is 
carried  out  upon  the  subject  (living  or  dead)  and  by  the 
use  of  the  skeleton. 

Action  of  the  gluteus  maximus. 

(i)  When  the  thigh  is  extended,  it  acts  as  an  external 
rotator  ;  its  upper  fibres  will  assist  abduction,  and  its 
lower  fibres  will  assist  adduction  ;  the  action  of  the  whole 
muscle  neutralizes  these  movements. 

(2)  When  the  thigh  is  flexed.  The  muscle  is  a  power- 
ful extensor  of  the  thigh,  it  is  also  a  strong  abductor  (in 
flexion) ;  abduction  diminishes  as  flexion  decreases  and  ex- 
tension increases  (in  other  words,  as  the  individual  assumes 
an  upright  position). 

(3)  Upon  the  leg,  it  will  assist  flexion  when  once  started, 
and  external  rotation,  through  the  iliotibial  band,  along 
with  the  tensor  vaginae  femoris. 

In  full  extension  of  the  leg  the  muscle  helps  to  main- 


604  A  MANUAL   OF  ANATOMY. 

tain  the  knee  in  that  position  and  to  resist  flexion,  yet  after 
flexion  is  once  started  its  action  (if  any)  is  as  indicated 
above. 

(4)  Upon  the  trunk.  Taking  its  fixed  point  from  below 
the  muscle  will  extend  the  trunk  upon  the  thighs  as  in 
assuming  an  upright  position  after  stooping  forward. 

The  action  of  the  gluteus  maximus  and  tensor  vaginae 
femoris,  through  the  attachment  of  the  iliotibial  band  is 
very  necessary  in  the  maintenance  of  the  trunk  erect  when 
standing  upon  one  leg.  They  act  here  Hke  the  guy  rope 
to  a  derrick  in  lifting  a  weight,  the  femur  being  the  up- 
right, the  pelvis  the  cross  beam,  and  the  body  the  weight ; 
the  centre  of  motion  being  at  the  hip  joint. 

The  Small  Sciatic  Nerve.      Fig.  126. 

The  small  sciatic  nerve  is  formed  by  branches  from  the 
second  and  third  sacral  nerves,  passes  through  the  great 
sacrosciatic  foramen  under  the  pyriformis  muscle,  then  be- 
neath the  gluteus  maximus  and  behind  the  fascia  lata 
through  the  middle  of  the  thigh  into  the  popliteal  space, 
where  it  pierces  the  deep  fascia  and  supplies  the  integu- 
ment over  the  popHteal  space  and  the  upper  third  of  the 
calf  of  the  leg. 

Its  Branches  are  : — 

(1)  Recurrent  cutaneous  branches  to  the  integument 
over  the  gluteus  maximus. 

(2)  The  inferior  pudendal.  This  branch  turns  inward 
under  the  gluteus  maximus,  pierces  the  deep  fascia  about 
an  inch  external  to  the  tuberosity  of  the  ischium  (see  page 
"406,)  and  runs  forward  to  supply  the  inner  side  of  the 
thigh  and  the  scrotum  (or  the  labium  majus). 

(3)  The  femoral  cutaneous  branches  supply  the  skin 
over  the  back  of  the  thigh  and  popliteal  space. 


THE  LOWER  EXTREMITY,  POSTERIOR.  605 

DISSECTION. 

Divide  the  gluteus  maximus  at  its  outer  and  middle  thirds  and  reflect  the 
two  portions. 

The  outer  portion  is  to  be  carefully  dissected  to  demonstrate  the  double 
insertion  of  the  muscle  and  the  bursa  between  it  and  the  great  trochanter, 
and  the  inner  portion  is  to  be  lifted  up  and  turned  back  on  to  the  sacrum  to 
show  its  extensive  origin  and  the  bursa  which  intervenes  between  the  muscle 
and  the  tuberosity  of  the  ischium. 

Divide  the  nerve  and  arterial  supply  close  to  the  muscle. 

Remove  entirely  the  inner  portion  of  the  muscle  by  cutting  it  away  from 
its  origins. 

A  larg-e  multilocular  bursa  will  be  found  between  the 
tendon  of  the  gluteus  maximus  and  the  great  trochanter 
of  the  femur.  A  second  one  intervenes  between  the  muscle 
and  the  tuberosity  of  the  ischium. 

Gluteus  Medius.      Figs.  ii8,  126,  127. 

Origin. — From  the  external  surface  of  the  ilium  between 
the  middle  curved  line  below  and  the  superior  curved  line 
and  the  anterior  four-fifths  of  the  external  lip  of  the  iliac  crest 
above,  from  the  deep  surface  of  the  fascia  lata  covering  it. 

Insertion. — Into  the  oblique  line  upon  the  outer  surface 
of  the  great  trochanter.  The  direction  of  this  oblique  line 
is  from  above  and  behind,  downward  and  forward. 

Neii'e  Supply. — The  superior  gluteal  (fourth  and  fifth 
lumbar,  and  first  sacral  nerves). 

Action.- — At  all  times  the  muscle  acts  as  an  abductor  of 
the  thigh,  and  serves  to  maintain  the  pelvis  level  when 
standing  upon  one  foot,  as  in  walking,  etc. 

The  anterior  portion  of  the  muscle  acts  as  an  internal 
(forward),  the  posterior,  as  an  external  (backward)  rotator 
of  the  thigh. 

Pyriformis.      Figs.  114,  126,  127. 

Origin. — From   the  front   of  the    lateral  margin   of  the 


606  A  MANUAL  OF  ANA  TOMY. 

second,  third,  and  fourth  pieces  of  the  sacrum,  and  from 
the  ridges  of  bone  between  the  first,  second,  third,  and 
fourth  sacral  foramina. 

From  the  deep  surface  of  the  great  sacrosciatic  ligament, 
and  the  upper  margin  of  the  great  sacrosciatic  notch. 

Insertion. — Into  the  upper  border  of  the  great  trochanter 
near  the  front.  The  tendon  of  the  pyriformis  muscle  is 
closely  joined,  near  the  trochanter,  to  the  common  tendon 
of  the  obturator  internus  and  the  gemelli  muscles.  If  the 
tendons  are  carefully  separated  it  will  be  found  that  the 
tendon  of  the  latter  muscles  passes  beneath  and  in  front  of 
that  of  the  former  muscle  ;  the  posterior  muscles  have  the 
anterior  insertion  into  the  great  trochanter. 

Nerve  Supply. — Muscular  branches  from  the  second  sacral 
nerve  of  the  sacral  plexus. 

Action. — If  the  thigh  is  extended  the  muscles  act  solely 
as  an  external  rotator.  When  the  thigh  is  flexed  it  acts  as 
an  abductor.  Acting  from  a  fixed  point  upon  the  trochan- 
ter the  pyriformis  will  carry  the  other  side  of  the  pelvis 
backward,  whether  the  femur  be  extended  or  flexed. 

Obturator  Internus  and  Gemelli.      Figs.  114,  126,  127. 

(i)  Obturator  internus.  From  the  inner  surface  of  the 
true  pelvis  (including  the  obturator  membrane),  below  a 
line  drawn  from  the  upper  margin  of  the  obturator  foramen 
to  the  junction  of  the  iliopectineal  line  near  its  ter- 
minus, and  above  a  line  drawn  about  the  base  of  the  spine 
of  the  ischium.  Behind  the  muscle  reaches  to  the  anterior 
margin  of  the  great  sacrosciatic  foramen,  and  in  front,  it 
extends  on  to  the  rami  of  the  pubes  and  ischium.  It  also 
arises  from  the  obturator  fascia  which  covers  it.  See 
page  398.  (2)  Gemellus  superior.  From  the  external 
surface  of  the  spine  of  the  ischium.      (3)   Gemellus  inferior. 


THE  LOIVER  EXTREMITY,   POSTERIOR.  607 

From  the  upper  and  back  part  of  the  tuberosity  of  the 
ischium,  along  the  lower  border  of  the  groove  for  the  ten- 
don of  the  obturator  externus.  The  tendon  of  the  obtura- 
tor internus  leaves  the  pelvis  through  the  small  sacrosciatic 
foramen ;  after  coming  through  the  foramen  it  receives  the  two 
gemelli  muscles,  the  superior  above  and  the  inferior  below, 
on  either  side.  These  small  muscles  are  really  portions  of 
the  obturator  internus  arising  external  to  the  pelvic  cavity. 

Iiiscrtion. — The  common  tendon  of  the  three  muscles  is 
attached  to  the  front  of  the  upper  margin  of  the  great  tro- 
chanter (in  front  of  the  pyriformis  as  explained.  See  Pyri- 
formis). 

Between  the  tendon  of  the  obturator  internus  and  the 
margin  of  the  small  sacrosciatic  foramen  is  a  large  bursa  ; 
another  one  may  exist  between  the  tendon  and  the  capsule 
of  the  hip  joint. 

Nerve  Supply. — By  muscular  branches  from  the  sacral 
plexus.  The  nerve  to  the  obturator  internus  gives  a  branch 
to  the  gemellus  superior,  while  the  gemellus  inferior 
receives  its  supply  from  the  nerve  to  the  quadratus  femoris. 
See  pages  6io,  612. 

Action. — To  rotate  the  thigh  outward  (external  rotators) 
when  the  limb  is  extended.  If  the  thigh  be  flexed  the 
muscles  act  as  abductors  of  it. 

The  femur  being  the  fixed  point,  the  opposite  side  of  the 
pelvis  will  be  carried  backward  in  extension  or  flexion. 

Quadratus  Pemoris.      Figs.  126,  127. 

Ongin. — From  the  outer  lip  of  the  tuberosity  of  the 
ischium. 

Insertion. — Into  the  linea  quadrati,  which  extends  verti- 
cally downward  from  the  middle  of  the  posterior  intertro- 
chanteric line  for  about  one  and  one-half  inches. 


608  A  MANUAL   OF  ANATOMY. 

Nerve  Supply. — A  branch  from  the  sacral  plexus,  see 
page  612. 

Action. — To  rotate  the  thigh  outward  and  adduct  it  when 
the  limb  is  extended.  If  the  thigh  is  flexed  it  acts  as  an 
external  rotator  and  abductor  of  it. 

Acting  from  the  femur,  it  will  depress  the  opposite  side 
of  the  pelvis  and  carry  it  backward. 

Obturator  Externus.      See  page  582. 

Biceps  Flexor  Cruris  (Pemoris)  {Biceps  Fenioris). 

Origin. — (1)  The  long  head,  in  common  with  the  semi- 
tendinosus  from  the  (anterior)  lower  and  internal  facet  upon 
the  tuberosity  of  the  ischium.  (2)  The  short  head,  from 
the  whole  length  of  the  external  lip  of  the  linea  aspera  and 
the  upper  two-thirds  of  the  external  condyloid  ridge,  and 
from  the  external  intermuscular  septum. 

Insertion. — Into  the  head  of  the  fibula  at  the  base  of  the 
styloid  process,  by  a  prolongation  of  some  of  the  anterior 
fibres  of  the  tendon  into  the  external  tuberosity  of  the 
tibia,  and  by  others  from  the  back  of  the  tendon  into  the 
deep  fascia  of  the  leg. 

Nerve  Supply. — The  great  sciatic  (from  the  first,  second,, 
and  third  sacral  nerves). 

Action. — (i)  Upon  the  leg  (both  heads)  the  biceps  is  a 
flexor  of  the  leg,  and  in  a  flexed  position  becomes  an  ex- 
ternal rotator  (supinator).  (2)  Upon  the  thigh  (the  long 
head)  the  muscle  is  an  extensor  for  all  the  ordinary  pur- 
poses of  locomotion  and  the  like,  the  gluteus  maximus 
being  only  called  into  action  by  some  heavier  work  to  be 
done.  It  also  has  a  slight  action  as  an  external  rotator  of 
the  thigh.  (3)  Upon  the  body,  it  is  used  in  raising  it  from 
a  stooping  position  (an  extensor  of  the  pelvis). 


THE  LOWER  EXTREMITY,  POSTERIOR.  609 

Semitendinosus.     Fig.  126. 

Origin. — By  a  tendon  common  to  it  and  the  long  head 
of  the  biceps  from  the  lower  (anterior)  and  internal  facet 
upon  the  tuberosity  of  the  ischium. 

Insertion. — By  a  long  slender  tendon  into  the  inner  sur- 
face of  the  tibia  opposite  its  tubercle,  where  it  lies  behind 
the  sartorius  and  below  the  gracilis.  Also,  into  the  deep 
fascia  of  the  leg. 

A  bursa  intervenes  between  the  three  tendons  and  the 
internal  lateral  ligament  of  the  knee. 

Nerve  Supply. — Great  sciatic.     See  biceps,  above. 

Action. — (i)  Upon  the  leg,  to  flex  the  leg  and  in  a  flexed 
position  to  rotate  it  inward  (pronation).  (2)  Upon  the 
thieh,  it  is  an  extensor,  and  used  for  the  lesser  muscular 
efforts.  (3)  Upon  the  pelvis  it  acts  as  an  extensor,  as  in 
raising  the  body  from  a  stooping  position. 

Semimembranosus.      Fig.  126. 

Origin. — From  the  external  and  upper  (posterior)  facet 
upon  the  tuberosity  of  the  ischium.  To  get  to  this  posi- 
tion the  tendon  of  the  semimembranosus  passes  forward  of, 
then  external  to,  the  common  tendon  of  the  long  head  of  the 
biceps,  and  the  semitendinosus  muscles. 

Insertion. — Into  the  transverse  groove  upon  the  back  of 
the  internal  tuberosity  of  the  tibia  ;  by  a  strong  recurrent 
bundle  of  fibres,  which  crosses  the  knee  joint  obliquely, 
into  the  outer  posterior  surface  of  the  external  condyle  of 
the  femur ;  and  by  a  continuation  of  the  direct  fibres  into 
the  fascia  covering  the  popliteus  muscle,  and  so  into  the 
oblique  line  upon  the  posterior  surface  of  the  tibia. 

Nerve  Supply. — The  great  sciatic,  the  filaments  coming 
from  the  first,  second,  and  third  sacral  nerves. 

Action. — (i)  Upon  the  leg,  the  muscle  acts  as  a  flexor, 
39 


610  A  MANUAL   OF  ANATOMY. 

and  in  flexion  to  rotate  the  leg  inward  (pronation).  (2) 
Upon  the  thigh,  it  has  the  same  action  as  the  semitendi- 
nosus.  (3)  Upon  the  body,  the  muscle  acts  as  the  semi- 
tendinosus. 

The  Great  Sciatic  Nerve.      Figs.   112,  114,  126,  127. 

This  is  the  largest  nerve  in  the  body.  It  is  formed 
within  the  pelvis  but  close  to  the  great  sacrosciatic  foramen, 
by  the  convergence  of  the  lumbosacral  cord,  the  first, 
second,  and  third  sacral  nerves  (anterior  branches,  see  page 

553)- 

It  emerges  through  the  great  sacrosciatic  foramen  being 

below  the  pyriformis  muscle,  and  descends  into  the  thigh 

until  at  its  lower  third,  when  it  divides  into  the  external  and 

internal  popliteal  nerves.     In  its  course  the   great  sciatic 

nerve  lies  between  the  tuberosity  of  the  ischium  and  the 

great  trochanter,  and  crosses  the  gemellus  superior,  tendon 

of  the  obturator  internus,  gemellus  inferior  (tendon  of  the 

obturator  externus),  the   quadratus  femoris,  and  adductor 

magnus  muscles. 

It  Hes  under  the  gluteus  maximus,  and  long  head  of  the 
biceps  muscles,  and  is  covered  by  the  fascia  lata,  superficial 
fascia  and  the  integument. 

In  the  upper  part  of  its  course  it  is  accompanied  by  the 
arteria  comes  nervi  ischiadici. 

Branches. — (i)  Muscular,  to  the  biceps,  semitendinosus, 
semimembranosus,  and  adductor  magnus.  (2)  Articular, 
to  the  hip  and  knee  joints.  The  latter  through  the  internal 
and  external  popliteal  branches. 

The  Internal  Pudic  Nerve.      See  page  413. 

The  Nerve  to  the  Obturator  Internus. 

This  branch  of  the  sacral  plexus  arises  from  the  second 


Fig.  127.  Dissection  of  Gluteal  Region. — i,  Origin  of  gluteus  medius.  2, 
Superior  gluteal  nerve.  3,  Inferior  branch  of  deep  division  (11)  of  gluteal  artery.  4, 
Gluteus  minimus.  5,  Stub  of  great  sciatic  nerve.  6,  Gemellus  superior.  7,  Obturator 
internus.  8,  Gemellus  inferior.  Look  for  the  obturator  externus  tendon  between  8 
and  19.  9,  Great  trochanter.  10,  Superior  branch  of  deep  division  of  gluteal  artery. 
II,  Deep  division  of  gluteal  artery.  12,  Superficial  division  of  gluteal  artery.  13, 
Pyriformis  reflected.  14,  Great  sacrosciatic  foramen  (filled  with  the  structures  it 
transmits).  15,  Internal  pudic  nerve.  16,  Internal  pudic  artery.  17,  Nerve  to  the 
obturator  internus  muscle.     iS,  Great  sacrosciatic  ligament.     19,  Quadratus  femoris. 


612  A  MANUAL  OF  ANATOMY. 

and  third  sacral  nerves,  issues  from  the  great  sacrosciatic 
foramen  below  the  pyriformis,  curves  around  the  base  of 
the  ischial  spine  and  re-enters  the  pelvic  cavity  and  is  dis- 
tributed to  the  obturator  internus  muscle. 

As  the  nerve  crosses  the  spine  it  gives  a  branch  to  the 
gemellus  superior.  Here  it  lies  external  to  the  internal 
pudic  artery.  (The  artery  lies  between  the  internal  pudic 
nerve  (internal)  and  the  nerve  to  the  obturator  internus 
(which  is  external).) 

The  Nerve  to  the  Quadratus  Femoris. 

This  muscular  branch  arises  from  the  third  sacral  nerve, 
leaves  the  pelvic  cavity  through  the  great  sacrosciatic 
foramen,  close  to  the  bone,  then  passes  under  (anterior  to) 
the  gemellus  superior,  tendon  of  obturator  internus,  and 
gemellus  inferior  muscles,  then  over  (posterior  to)  the  ten- 
don of  the  obturator  externus  to  the  anterior  surface  of  the 
quadratus  femoris  to  which  it  is  supplied. 

The  gemellus  inferior  is  supplied  by  a  branch  from  this 
nerve. 

The  Gluteal  Artery.      Figs.  112,  114,  126,  127. 

This  is  the  largest  of  the  three  arteries  which  leave  the 
pelvis  through  the  great  sacrosciatic  foramen.  It  is  really 
the  continuation  of  the  posterior  division  of  the  internal 
iliac  and  passes  out  through  the  great  sacrosciatic  foramen 
above  the  pyriformis  muscle,  close  to  the  bone.  A  half- 
inch  from  the  margin  of  the  foramen  it  divides  into  a 
superficial  and  deep  branch. 

( I )  The  superficial  branch.  This  breaks  up  into  branches 
which  ramify  beneath  and  within  the  gluteus  maximus 
muscle  and  supply  the  surrounding  parts.  (2)  The  deep 
branch.  Gives  a  nutrient  artery  to  the  ilium  and  then 
divides  into  a  superior  and  an  inferior  branch,  which  pass 


THE  LOWER  EXTREMITY,  POSTERIOR.  613 

outward  and  forward  between  the  gluteus  medius  and  mini- 
mus muscles  ;  the  superior  keeping  close  to  the  bone  along 
the  origins  of  the  muscles,  the  inferior  keeping  company 
with  the  superior  gluteal  nerve.  (3)  Besides  these  branches, 
the  gluteal  artery  gives  off  within  the  pelvic  cavity  small 
vessels  to  the  obturator  internus,  pyriformis,  levator  ani, 
and  coccygeus  muscles  and  the  pelvis  itself 

The  gluteal  artery  anastomoses  with  the  lateral  sacral, 
sciatic,  deep  circumflex  iliac,  and  the  external  circumflex 
(of  the  profunda). 

The  Internal  Pudic  Artery.     See  page  411. 

The  Sciatic  Artery.      Figs.  112,  114,  126,  127. 

This  is  the  larger  branch  of  bifurcation  of  the  anterior 
division  of  the  internal  iliac.  It  comes  through  the  great 
sacrosciatic  foramen  below  the  pyriformis  muscle  and 
passes  downward  under  the  gluteus  maximus  to  terminate 
in  the  upper  part  of  the  thigh. 

It  supplies  numerous  branches  to  the  surrounding  parts, 
a  few  of  which  are  named. 

(i)  The  coccygeal  branch  ;  this  pierces  the  great  sacro- 
sciatic ligament,  and  supplies  the  gluteus  maximus  and  the 
superficial  parts  over  the  coccyx  and  sacrum.  (2)  The 
a7iasto))iotic,  a  long  slender  branch  to  the  great  trochanter, 
around  which  it  anastomoses  with  the  gluteal,  external  cir- 
cumflex, ascending  branch  of  the  internal  circumflex,  and 
the  first  perforating  of  the  profunda.  It  supplies  the  exter- 
nal rotators  of  the  thigh  and  the  hip  joint.  (3)  Comes 
nctid  ischiadici,  a  small  branch  which  supplies  the  great 
sciatic  nerve.  (4)  Numerous  cutaneous  branches  below 
the  gluteus  maximus.  The  sciatic  artery  through  its  lower 
branches  anastomoses  with  the  first  perforating  of  the  pro- 


614  A  MANUAL  OF  ANATOMY. 

funda  (below),  the  external  circumflex,  and  the  internal 
circumflex  upon  the  outer  and  inner  sides  of  the  femur. 
This  arrangement  of  ■  communicating  branches  constitutes 
the  "crucial  anastomosis."  The  student  must  not  expect 
to  find  the  inosculating  branches  forming  any  well  defined 
"cross."  However,  as  one  artery  (the  sciatic)  is  above, 
another  (first  perforating)  is  below,  and  two  others  upon 
either  side  (the  external  and  internal  circumflex)  a  some- 
what "cross-shaped"  anastomosis  is  formed.  (5)  Within 
the  pelvis  the  sciatic  gives  twigs  to  the  adjacent  muscles^ 
nerves,  and  pelvic  viscera. 

The  Great  Sacrosciatic  Lig-ament.     Figs.  126,  114. 

This  is  a  very  strong  band  of  fibres  extending  from  the 
posterior,  superior,  and  inferior  iliac  spines,  and  from  the 
side  and  posterior  surface  of  the  sacrum  and  coccyx  to  the 
inner  margin  of  the  tuberosity  of  the  ischium,  along  which 
it  is  prolonged  as  a  long  curved  band  (the  falciform  pro- 
cess) for  an  inch  and  a  half 

A  part  of  the  fibres  of  the  great  sacrosciatic  ligament 
pass  into  the  tendon  of  the  long  head  of  the  biceps  (flexor 
biceps  femoris). 

This  muscle  then  may  be  said  to  take  an  origin  from  the 
surface  from  which  this  ligament  rises. 

The  great  sacrosciatic  ligament  converts  the  small  sacro- 
sciatic notch  into  a  foramen  (assisted  by  the  small  ligament 
of  the  same  name). 

From  the  posterior  surface  of  the  ligament  the  gluteus 
maximus  arises  ;  from  the  anterior  surface  some  fibres  of 
the  pyriformis. 

To  the  outer  margin  the  deeper  lamina  of  the  fascia  lata 
is  attached  ;  at  its  inner  border  it  becomes  continuous  with, 
the  obturator  fascia. 


THE  LOWER  EXTREMITY,  POSTERIOR.  015 

It  is  usually  pierced  by  the  coccygeal  branch  of  the 
sciatic  artery. 

The  Small  Sacrosciatic  Ligament.       Fig.  114. 

This  arises  from  the  side  of  the  sacrum  and  coccyx,  an- 
terior to  the  great  sacrosciatic  ligament,  with  which  it  blends. 

It  is  inserted  into  the  spine  of  the  ischium.  It  converts 
the  great  sacrosciatic  notch  into  a  foramen  (assisted  by  the 
great  sacrosciatic  ligament  to  a  slight  extent).  From  it 
arise  some  fibres  of  the  coccygeus  muscle. 

The  Sacrosciatic  Foramina.      Figs.  114,  127. 

These  are  formed  by  the  great  and  small  sacrosciatic 
ligaments  bridging  over  the  great  and  small  sacrosciatic 
notches  as  mentioned  above. 

The  greater  foramen  transmits  the  pyriformis  muscle  ; 
above  the  muscle  the  gluteal  artery  and  vein  and  the  supe- 
rior gluteal  nerve.  Below  the  muscle  the  sciatic  artery  and 
vein,  the  great  and  small  sciatic  nerves,  the  internal  pudic 
artery,  vein,  and  nerve,  and  the  nerves  to  the  obturator 
internus  and  quadratus  femoris  muscles. 

The  smaller  foramen  transmits  the  obturator  internus 
muscle  (its  tendon),  the  internal  pudic  artery,  vein,  and 
nerve,  and  the  nerve  to  the  obturator  internus  muscle. 

DISSECTION. 
Cut  through  the  gluteus  medius  at  its  outer  and  middle  thirds.     Reflect  the 
two  parts. 

Gluteus   Minimus.      Figs.   118,  127. 

Origin. — From  the  external  surface  of  the  ilium  between 
the  middle  and  inferior  curved  lines,  extending  from  the 
margin  of  the  great  sacrosciatic  notch  behind,  to  the  notch 
between  the  anterior,  superior,  and  inferior  spines  of  the 
ilium. 


616  -  A  MANUAL   OF  ANA  TOMY. 

Insertion. — Into  a  rough  area  upon  the  front  of  the  great 
trochanter. 

A  small  bursa  is  found  between  the  tendon  and  the  tro- 
chanter. 

Nerve  Supply. — The  superior  gluteal ;  see  Gluteus  inedius, 
page  605. 

Action. — The  same  as  the  gluteus  medius,  only  in  a  less 
degree. 

It  is  an  abductor  of  the  thigh  ;  the  anterior  portion  of 
the  muscle  rotates  the  thigh  forward  (inward),  and  the  pos- 
terior portion  backward  (outward).  It  acts  upon  the  pelvis 
to  keep  it  level  or  bring  the  crest  toward  the  great  trochan- 
ter, also  to  swing  the  other  side  forward,  as  in  walking. 

The  Superior  Gluteal  Nerve.     Fig.  127. 

This  is  formed  by  a  branch  from  the  lumbosacral  cord 
and  the  first  sacral  nerve.  Its  course  is  through  the  great 
sacrosciatic  foramen  above  the  pyriformis  muscle,  forward 
between  the  gluteus  medius  and  minimus  muscles,  which  it 
supplies,  and  terminates  in  the  deep  surface  of  the  tensor 
vaginae  femoris  muscle  (see  page  551). 

DISSECTION. 
Remove  the  integument  from  the  back  of  the  leg,  following  the  general 
directions  on  page  600  for  exposing  the  thigh. 

When  the  heel  is  reached,  cut  the  skin  flap  away  entirely. 

The  External  or  Short  Saphenous  Nerve.  Figs.  122, 
128. 

This  is  formed  at  the  middle  of  the  back  of  the  leg,  su- 
perficial to  the  deep  fascia  (the  branches  which  form  it 
having  pierced  the  deep  fascia  already),  by  the  tibial  and 
fibular  communicating  cutaneous  nerves. 

It  descends  along  the  outer  surface  of  the  \&%,  curves 
forward  below  the  external  malleolus,  and  runs  along  the 


Fig.  128.  Dissection  of  the  Popliteal  Space. — i,  Short  head  of  biceps.  2, 
External  popliteal  nerve.  3,  Comniunicans  peronei.  4,  Communicans  tibialis.  5, 
Gastrocnemius.  6,  Great  sciatic  nerves.  7,  Muscular  branch  to  semimembranosus. 
8,  Last  perforating  artery.  9,  Semitendinosus.  10,  Semimembranosus.  11,  Tendon  of 
adductor  magnus.  12,  Popliteal  arteries.  13,  Popliteal  veins.  14,  Internal  popliteal 
nerves.  15,  Internal  superior  articular  artery.  16,  Gracilis.  17,  Ner\'e  to  inner  head 
gastrocnemius.  18,  Inferior  muscular  (sural)  arteries.  19,  Tendon  of  Sartorius.  20, 
Inner  head  gastrocnemius.  21,  Inferior,  internal  articular  artery.  22,  Short  head  of 
biceps.  23,  Long  head  of  biceps  (divided).  24,  External  popliteal  nerve.  25,  Supe- 
rior, external  articular  artery.  26,  Nerve  to  outer  head  of  gastrocnemius.  27,  Inferior 
muscular  (sural)  arteries.  28,  Plantaris.  29,  Outer  head  gastrocnemius.  30,  Nerve  to 
soleus.    31,  Soleus. 


618    .  A  MANUAL  OF  ANATOMY. 

outer  border  of  the  foot  and  little  toe,  Avhere  it  terminates. 
The  nerve  communicates  with  the  musculocutaneous  on  the 
dorsum  of  the  foot,  supplies  the  integument  along  its  course, 
and  is  accompanied  by  the  external  saphenous  vein. 

The  External  or  Short  Saphenous  Vein. 

For  its  formation,  see  page  586. 

The  vein  follows  upward  along  the  outer  part,  then  the 
back  of  the  leg  to  the  middle  of  the  popliteal  space,  where 
it  pierces  the  deep  fascia  and  empties  into  the  popliteal 
vein.  Its  tributaries  are  numerous  cutaneous  veins  from 
the  outer  and  back  parts  of  the  foot  and  leg,  and  a  large 
descending  one  from  the  back  of  the  thigh.  It  communi- 
cates with  the  deep  veins  through  the  deep  fascia,  and  with 
the  internal  saphenous  near  its  termination. 

The  Deep  Fascia.     See  page  584. 

DISSECTION. 
After  cutting  through  the  fascia  in  the  middle  line  remove  it  together  with, 
the  external  saphenous  vein,  but  leave  the  nerve  behind. 
Clean  out  the  popliteal  space. 

The  External  Popliteal  Nerve.      Fig.  128. 

This  is  the  outer  branch  of  bifurcation  of  the  great 
sciatic  nerve,  and  runs  from  the  upper  part  of  the  popliteal 
space  along  the  inner  border  of  the  tendon  of  the  biceps 
muscle  to  the  neck  of  the  fibula,  around  which  it  turns,  lying 
close  to  the  bone  and  covered  by  the.  peroneus  longus 
muscle.  Here  it  divides  into  its  two  terminal  branches, 
musculocutaneous  and  the  anterior  tibial,  for  which  see 
pages  588  and  598. 

Branches  of  the  External  Popliteal. 

(i)  Articular,  to  the  knee  joint,  which  they  reach  by  fol- 
lowing the  superior  and  inferior  external  articular  branches. 


THE  LOWER  EXTREMITY,  POSTERIOR.  619 

of  the  popliteal  artery.  (2)  Cutaneous.  Two  in  number, 
one  to  the  upper  and  outer  part  of  the  leg.  The  other 
(the  fibular  communicating,  peroneal,  or  nervus  communi- 
cans  peronci)  passes  to  the  back  of  the  calf,  where  at  the 
middle  of  the  leg  it  joins  with  the  tibial  communicating 
(nervus  communicans  tibialis)  to  form  the  short  or  external 
saphenous  nerve.  (3)  The  recurrent  articular  nerve,  a 
small  branch  at  the  point  of  bifurcation  of  the  external 
popliteal ;  it  follows  the  anterior  tibial  recurrent  artery  to 
the  front  of  the  knee. 

The  Internal  Popliteal  Nerve.      Fig.  128. 

This  is  larger  than  the  external  popliteal  and  is  the  direct 
continuation  of  the  great  sciatic.  It  extends  from  the  bi- 
furcation of  the  great  sciatic  vertically  through  the  middle 
of  the  popliteal  space  and  becomes  the  posterior  tibial  at 
the  lower  border  of  the  popliteus  muscle. 

The  nerve  is  the  most  superficial  of  the  important  con- 
tents of  the  popliteal  space.  In  the  upper  third  it  lies  ex- 
ternal to  the  popliteal  vessels,  in  the  middle  directly  behind 
them,  and  in  the  lower  third  to  their  inside.  In  front  of 
the  nerve  lies  the  popliteal  vein  and  in  front  of  the  vein  the 
artery.  The  order  then  is,  from  behind  forward,  nerve,  vein, 
and  artery. 

Branches. 

(i)  Articular,  to  the  inner  side  and  back  of  the  knee 
joint  being  found  with  the  superior  and  inferior  internal 
and  azygos  articular  branches  of  the  popliteal.  (2)  Cuta- 
neous, this  is  the  tibial  communicating  (nervus  communicans 
tibialis).  It  is  given  off  the  internal  popliteal  nerve  at  the 
middle  of  the  popliteal  space,  descends  in  the  interval  be- 
tween the  two  heads  of  the  gastrocnemius,  pierces  the  deep 
fascia  of  the  leg,  is  joined  by  the  fibular   communicating, 


620  A  MANUAL   OF  ANATOMY. 

and  the  trunk  becomes  the  external  saphenous.  (3)  The 
muscular  branches.  These  supply  the  gastrocnemius,  plan- 
taris,  popliteus,  and  soleus,  muscles. 

Gastrocnemius,     Figs.  128,  129,  131. 

Origin. — By  two  heads  from  the  posterior  surface  of  the 
femur  above  each  condyle  and  from  the  condyloid  ridges 
of  the  same. 

Insertion. — By  the  tendo-Achillis,  common  to  it  and  the 
soleus,  into  the  lower  part  of  the  posterior  surface  of  the 
OS  calcis. 

A  bursa  is  found  under  the  inner  head  of  the  muscle 
and  another  between  the  tendo-Achilhs  and  the  upper  part 
of  the  OS  calcis. 

Nerve  Supply. — The  internal  popliteal. 

Action. — To  flex  the  leg  upon  the  thigh,  to  extend  the 
foot  upon  the  ankle. 

In  the  first  case  the  muscle  acts  with  the  flexors  of  the 
knee,  and  in  the  second  with  the  extensors  of  the  foot  and 
ankle. 

The  Popliteal  Space.     Fig.  128. 

This  is  the  hollow  behind  the  knee  joint.  It  is  diamond- 
shaped. 

Its  boundaries  are  formed  as  follows  : — 

Above,  the  biceps  externally,  the  semitendinosus,  semi- 
membranosus, the  gracilis,  and  the  sartorius,  internally. 
Below,  by  the  diverging  heads  of  the  gastrocnemius  and  in 
addition  the  plantaris  at  the  outer  side.  On  either  side  of 
the  middle  of  the  space  are  the  condyles  of  the  femur. 

The  "floor"  of  this  space  is  formed  by  the  back  of  the 
lower  end  of  the  femur,  the  posterior  ligament  of  the  knee 
joint,  the  posterior  part  of  the  articular  rim  of  the  tibia 
(covered  by  the  above  ligament)  and  the  popliteus  muscle 


THE  LOWER  EXTREMITY,  POSTERIOR.  621 

(covered  by  the  aponeurosis  derived  from  the  tendon  of  the 
semimembranosus  muscle).  The  contents  of  this  space,  are  : 
The  popliteal  artery,  vein,  nerves,  and  their  branches  ;  the 
small  sciatic  and  terminal  branch  of  the  obturator  nerves  ; 
the  external  or  short  saphenous  vein  ;  lymphatic  glands, 
and  adipose  tissue. 

The  relatiojis  of  the  artery,  vein  and  nerves. — The  popli- 
teal nerves  are  the  most  superficial,  the  external  running 
along  the  inner  edge  of  the  tendon  of  the  biceps  muscle, 
the  internal  descending  vertically  through  the  space.  The 
vein  is  deeper  than  the  nerve  and  slightly  internal  to 
it  (in  the  upper  part  of  the  space).  The  artery  is  still 
deeper  than  the  vein  (in  close  union  with  it)  and  a  little  to 
its  inner  side  (in  the  upper  half  of  the  space). 

DISSECTION. 

Divide  the  two  branches  that  go  to  form  the  external  saphenous  nerve,  and 
the  inner  and  outer  head  of  the  gastrocnemius  just  above  their  junction. 

Turn  the  lower  part  of  the  muscle  downward  and  separate  the  upper  heads, 
saving  their  nerve  supply.     Clean  the  parts  presenting 

Plantaris.      Figs.  128,  129,  131, 

Origin. — From  the  lower  part  of  the  external  bifurcation 
of  the  linea  aspera,  the  posterior  surface  of  the  femur  ad- 
jacent thereto,  and  from  the  posterior  ligament  of  the  knee 
joint. 

Insertion. — By  a  long  slender  tendon  which  descends 
between  the  gastrocnemius  and  the  soleus  to  be  attached 
into  the  os  calcis  at   the   inner  side  of  the  tendo-Achillis. 

Nerve  Supply. — The  internal  popliteal. 

Action. — A  feeble  flexor  of  the  leg  upon  the  thigh,  and 
extensor  of  the  foot  upon  the  leg. 

Popliteus.      Fig.  130. 

Origin. — From    the   anterior  portion    of  the    transverse 


622  '         A  MANUAL   OF  ANATOMY. 

groove  near  the  lower  margin  of  the  external  condyle  of 
the  femur,  from  the  posterior  ligament  of  the  knee  joint. 

Insertion. — Into  the  triangular  surface  of  the  tibia  above 
the  oblique  line,  and  into  the  deep  surface  of  the  aponeurosis 
which  covers  the  muscle. 

Nerve  Supply. — The  internal  popliteal,  which  distributes 
a  branch  to  the  anterior  surface  of  the  muscle. 

Action. — To  flex  the  leg  upon  the  thigh  ;  in  flexion  it 
will  rotate  the  leg  internally  (pronation). 

When  the  leg  is  extended  the  tendon  of  the  muscle  crosses 
the  transverse  groove  upon  the  external  condyle  ;  in  flexion 
the  tendon  lies  in  the  groove. 

Soleus,      Figs.  129,  131. 

Oi'igin. — From  the  posterior  surface  of  the  head  of  the 
fibula  and  the  upper  third  of  the  same,  from  the  external 
intermuscular  septum,  from  the  obHque  line  and  from  the 
inner  border  of  the  tibia  as  low  as  the  middle  of  the  bone, 
from  a  tendinous  arch  which  joins  the  back  of  the  tibia 
and  fibula,  and  covers  the  popliteal  vessels  and  nerves. 

Insertion. — By  the  tendo-Achillis,  which  it  helps  form, 
into  the  lower  part  of  the  posterior  surface  of  the  os  calcis. 

Nerve  Supply. — The  internal  popliteal. 

Action. — To  extend  the  foot,  as  in  raising  the  body  in 
walking,  etc. 

The  Tendo-Achillis.      Figs.  129,  131. 

This  is  the  strongest  tendon  in  the  body.  It  is  formed 
by  the  junction  of  the  tendons  of  the  gastrocnemius  and 
soleus  muscles,  and  is  attached  to  the  lower  part  of  the 
posterior  surface  of  the  os  calcis.  Its  dimensions  are  length, 
from  the  middle  of  the  leg  to  the  heel,  three  to  five  inches, 
five-eighths  of  an  inch  wide,  three-eighths  of  an  inch 
thick. 


THE  LOWER  EXTREMITY,  POSTERIOR.  623 

The  Popliteal  Vein.      Fig.  128. 

The  popliteal  vein  is  formed  b}-  the  junction  of  the  venae 
comites  of  the  anterior  and  posterior  tibial  arteries,  at  the 
lower  border  of  the  popliteus  muscle,  and  passing  up^\•ard 
becomes  the  femoral  vein  at  the  opening  in  the  adductor 
magnus  muscle.  Its  relation  to  the  popliteal  arter}-.  It 
lies  behind  the  artery  and  crosses  it  slightly  obHquely  from 
below  upward,  and  from  the  inner  to  the  outer  side. 

The  Popliteal  Artery.      Figs.  128,  129,  1 30. 

The  popliteal  artery  is  a  continuation  of  the  femoral  from 
the  opening  in  the  adductor  magnus  muscle  to  the  lower 
border  of  the  popliteus  muscle,  where  it  terminates  by 
dividing  into  the  anterior  and  posterior  tibial  arteries 
opposite  the  lower  margin  of  the  tibial  tubercle.  The  course 
of  the  arter}'  is  indicated  by  a  line  drawn  vertically  through 
the  popliteal  space. 

Relations. — The  artery  rests  upon  the  floor  of  the  popliteal 
space,  which  is  formed  by  the  posterior  surface  of  the  lower 
end  of  the  femur,  the  posterior  ligament  of  the  knee  joint, 
the  posterior  margin  of  the  tibia  (covered  by  the  posterior 
ligament),  and  the  popliteus  muscle,  from  which  it  is 
separated  by  the  fascia  covering  the  muscle. 

The  popliteal  vein  lies  close  behind  the  arter}^  being  a 
little  external  to  it  above,  and  slightly  internal  to  it  below. 

The  internal  popliteal  nerve  is  behind  (or  superficial  to) 
both  artery  and  vein,  and  crosses  them  about  the  middle  of 
the  space,  from  the  outer  to  the  inner  side  (above  down- 
ward). 

The  semimembranosus  muscle  covers  the  upper  part  of 
the  artery  (vein  and  nerve),  the  inner  head  of  the  gastroc- 
nemius, the  lower  part  of  it,  the  fascia  (tvvo  la}-ers)  and 
inteeument  for  its  entire  course. 


624  A  MANUAL  OF  ANATOMY. 

The  artery  lies  between  the  semimembranosus  and  biceps 
above,  and  between  the  two  heads  of  the  gastrocnemius 
below,  the  plantaris  being  at  the  outer  side. 

Branches  of  the  Popliteal. 

(i)  Muscular  or  sural.  These  are  divided  into  two 
groups,  superior  and  inferior,  from  the  upper  and  lower  por- 
tions of  the  popliteal. 

The  superior  are  three  or  four  in  number,  supply  the 
structures  of  the  upper  half  of  the  popliteal  space  and  anas- 
tomose with  the  lower  perforating  branches  of  the  profunda, 
and  the  superior  articular  branches  of  the  popliteal. 

The  inferior  sural,  two  in  number,  supply  the  muscles  at 
the  lower  part  of  the  popliteal  space  and  calf  of  the  leg. 

From  the  inferior  sural  cutaneous  branches  are  given  off 
to  the  superficial  structures  upon  the  back  of  the  leg. 

A  larger  branch  may  accompany  the  external  saphenous 
vein  ;  if  present  it  is  called  the  external  saphenous  artery. 

(2)  Articular.  Five  in  number.  Figs.  119,  121,  128, 
129,  130.  {a)  The  superior  external  articular.  Passes 
transversely  outward  above  the  external  head  of  the 
gastrocnemius  and  under  (in  front  of)  the  biceps  to 
the  front  of  the  outer  side  of  the  upper  part  of  the 
knee,  where  it  anastomoses  with  the  descending  branch 
of  the  external  circumflex,  above  ;  the  deep  branch 
from  the  anastomotica  magna  and  the  superior  internal 
articular,  across  the  front  of  the  knee ;  and  the  inferior 
external  articular,  below,  {p)  The  inferior  external  articu- 
lar. This  takes  a  course  outward  under  (in  front  of)  the 
external  head  of  the  gastrocnemius,  then  under  the  external 
lateral  ligament  of  the  knee  and  tendon  of  the  biceps  muscle 
(just  above  the  head  of  the  fibula)  to  the  front  of  the  lower 
part  of  the  knee,  where  it  anastomoses  with  the  external 
superior  external  articular,  above  ;  the  anterior  tibial  recur- 


Fig.  129.  Dissection  of  Leg,  Posterior.— i,  Great  sciatic  nerve.  2,  Tendon 
of  adductor  magnus.  3,  Popliteal  artery.  4,  Popliteal  vein.  5,  Popliteal  nerve.  6, 
7,  8,  9,  10,  see  15,  17,  18,  20,  21,  Fig.  128.  11,  Popliteus.  12,  Tendon  of  plantaris. 
13,  Posterior  tibial  nerve.  14,  Posterior  tibial  artery.  15,  16,  17,  18,  19,  20,  21,  see  23, 
24,  25,  26,  27,  28,  29,  Fig.  128.  22,  Soleus.  23,  Lower  part  of  gastrocnemius.  24, 
Tendo-Achillis.     25,  26,  Tendons  of  peroneus  longus  and  brevis. 

Fig.  130. — I,  Internal  inferior  articular  artery.  2,  Popliteus  muscle.  3,  3,  Poste- 
rior tibial  artery.  4,  Flexor  longus  digitorum.  5,  Tendon  of  tibialis  posticus.  6, 
Great  sciatic  nerve.  7,  Internal  and  8,  External  popliteal  nerves.  9,  Biceps  tendon. 
ID,  External  inferior  articular  artery.  11,  Head  of  fibula.  12,  Peroneal  artery.  13,13, 
Posterior  tibial  nerve.    14,  Flexor  longus  hallucis.     15,  Os  calcis. 

40 


626  A  MANUAL  OF  ANA  TOMY. 

rent,  below  ;  and  the  internal  inferior  articular  across  the 
front  of  the  knee.  (r)  The  superior  internal  articular. 
Arises  from  the  popliteal  opposite  the  external  articular. 
It  runs  inward  along  the  insertion  of  the  inner  head  of  the 
gastrocnemius,  then  under  (in  front  of)  the  tendons  of  the 
inner  ham-string  and  adductor  magnus  muscles  to  the  front 
of  the  upper  part  of  the  knee  and  here  anastomoses  with 
the  deep  branch  of  the  anastomotica  magna,  above  ;  the 
superior  external  articular,  across  the  front  of  the  knee  ;  and 
the  inferior  internal  articular,  below,  {d^  The  inferior 
internal  articular.  Takes  a  course  downward  and  in- 
ward under  (in  front  of)  the  inner  head  of  the  gastroc- 
nemius muscle,  lying  upon  the  popliteus  muscle,  then 
passes  between  the  internal  lateral  ligament  and  the  tibia, 
to  the  front  of  the  lower  part  of  the  joint.  Here  it 
ends  in  branches  which  anastomose  with  the  inferior 
external  articular,  over  the  front  of  the  tibia ;  and  the 
superior  internal  articular,  and  superficial  branch  of  the 
anastomotica  magna  above.  {e)  The  azygos  articular. 
This  comes  off  the  front  of  the  popliteal,  at  the  middle 
of  the  back  of  the  knee  and  passes  directly  forward  into 
the  joint. 

The  arterial  anastomosis  about  the  knee  joint  is  arranged 
in  a  superficial  and  deep  system.  The  former  lying  between 
the  integument  and  fascia  and  the  latter  close  to  the  bones. 

DISSECTION. 

Divide  the  tendon  of  the  plantaris  and  tendo-Achillis  near  their  insertion 
and  cut  the  soleus  away  from  its  tibial  origin. 

Turn  the  muscles  outward.  Clean  the  deep  layer  of  muscles,  and  the 
vessels  and  nerves. 

Inasmuch  as  the  deep  muscles  of  the  leg  pass  to  their 
insertion  into  the  foot  this  part  of  them  has  not  been  dis- 
sected out  at  present. 


THE  LOWER  EXTREMITY,  POSTERIOR.  627 

They  will  be  described  at  this  time  however,  and  the 
student  can  revaew  them  after  the  foot  has  been  dissected. 

Flexor  Long-US  Digitorum.      Figs.  130,  131,  133. 

Origin. — From  the  posterior  surface  of  the  tibia,  extend- 
ing from  the  oblique  line  to  the  junction  of  the  middle  and 
lower  thirds  of  the  bone,  from  the  deep  fascia  which  covers 
the  muscle,  and  from  the  intermuscular  septum. 

Insertion  (see  Dissection  of  Foot). — Into  the  bases  of 
the  last  phalanges  of  the  four  outer  toes. 

The  tendon  of  the  muscle  occupies  a  special  fibrous  canal 
lined  with  synovial  membrane  behind  the  internal  malleolus 
(being  posterior  to  the  tendon  for  the  tibialis  posticus). 
Turning  forward  into  the  foot  the  tendon  crosses  below 
that  for  the  flexor  longus  hallucis,  to  which  it  is  connected 
by  a  fibrous  band,  then  receives  the  insertion  of  the  flexor 
accessorius  and  divides  into  the  four  terminal  tendons  ;  they 
then  pass  through  a  button-hole  slit  in  the  tendons  of  the 
short  flexor  and  on  to  their  insertion.  (See  the  Lnmbri- 
cales. 

Nerve  Supply. — The  posterior  tibial. 

Action. — To  flex  the  toes,  beginning  with  the  last  pha- 
langes and  passing  backward,  to  flex  the  joints  of  the  foot 
(mediotarsal),  to  extend  the  foot. 

Plexor  Longus  Hallucis  (Pollicis).     Figs.  130,  131,  133. 

Origin. — From  the  posterior  (and  internal)  surface  of  the 
fibula  for  its  lower  two-thirds,  from  the  deep  surface  of  the 
fascia  which  covers  the  muscle,  from  the  intermuscular 
septa  on  either  side. 

Insertion  (see  Dissection  of  Foot). — Into  the  base  of 
the  last  phalanx  of  the  great  toe. 

The  tendon  of  this  muscle  slightly  grooves  the  back  of 
the  tibia  and  astragalus,  passes  forward  under  the  sustenta- 


628'  A  MANUAL  OF  ANATOMY. 

culum  tali ;  for  this  distance  the  tendon  is  contained  in  a 
fibrous  canal  lined  with  synovial  membrane.  It  continues 
forward  above  the  tendon  of  the  flexor  longus  digitorum,  to 
which  it  gives  a  slip,  and  passes  to  its  insertion. 

Nerve  Supply. — The  posterior  tibial. 

Action. — To  flex  the  great  toe,  to  flex  the  mediotarsal 
joints  of  the  foot,  to  extend  the  foot  upon  the  leg. 

The  two  above  muscles  are  intimately  concerned  in 
walking  and  all  allied  acts  ;  by  their  contraction  the  integ- 
rity of  the  arch  of  the  foot  is  preserved. 

Tibialis  Posticus.     Figs.  130,  131. 

Origin. — From  the  posterior  surface  of  the  tibia  external 
to  the  origin  of  the  flexor  longus  digitorum,  and  extending 
from  the  obHque  line  to  the  middle  and  lower  thirds  of  the 
shaft ;  from  the  postero-internal  surface  of  the  fibula  internal 
to  the  origins  of  the  soleus  and  the  flexor  longus  hallucis, 
and  extending  from  the  neck  to  the  lower  fourth  of  the 
shaft ;  from  the  posterior  surface  of  the  interosseous  mem- 
brane for  its  upper  three-fourths  ;  from  the  intermuscular 
septa  on  either  side  and  from  the  surface  of  fascia  covering 
the  three  deep  muscles  of  the  leg. 

Insertion  (see  Fooi^. — Into  the  tubercle  of  the  scaphoid, 
the  OS  calcis  (anterior  part  of  the  sustentaculum  tali), 
the  under  surface  of  the  base  of  the  first  metatarsal, 
three  cuneiform  and  cuboid  bones,  by  a  broad  expansion  of 
the  tendon  of  the  muscle  which  passes  into  the  ligaments 
which  bind  the  bones  of  the  foot  together.  The  tendon 
of  the  muscle  passes  behind  the  internal  malleolus,  being 
the  most  anterior  of  the  structures  at  this  place.  In  this 
course  it  is  contained  in  a  stout  fibrous  canal  lined  with 
synovial  membrane. 

Nerve  Supply. — The  posterior  tibial. 


Fig.  131.  Dissection  of  Leg  and  Foot,  Posterolateral  Region.— i,  Popliteus. 
2,  Flexor  longus  digitorum.  3.  Tibialis  posticus.  4,  Dorsalis  pedis  artery.  5,  Ten- 
don (divided)  tibialis  anticiis.  6,  Tendon  of  peroiieus  longus.  7,  Flexor  brevis  hal- 
lucis.  8,  Adductor  hallucis.  9,  Transverse  pedis.  10,  Internal  and  external  plantar 
arteries.  11,  External  plantar  nerve.  12,  Cut  end  of  internal  plantar  nerve.  13,  In- 
ternal calcanean  nerve.  14,  Os  calcis.  15,  Internal  annular  ligament.  16,  Tendo- 
Achillis  and  tendon  of  plantaris.  17,  Posterior  tibial  artery.  18,  Posterior  tibial  nerve. 
19,  Flexor  longus  hallucis.  20,  Soleus.  21,  Plantaris.  '22,  Gastrocnemius.  23,  In- 
ternal popliteal  nerve.    24,  Popliteal  artery. 


630'  A  MANUAL  OF  ANATOMY. 

Action. — To  extend  the  foot  upon  the  ankle,  to  adduct 
the  foot,  to  raise  the  inner  border  of  the  sole  (inversion). 
The  action  of  this  muscle  tends  to  prevent  the  production 
of  flat  foot  by  holding  the  tarsal  bones  firmly  together,  and 
inverting  the  sole. 

Peroneus  Longus,     Figs,  123,  124,  134. 

Origin. — From  the  external  tuberosity  of  the  tibia,  from 
the  outer  surface  of  the  head  and  upper  two-thirds  of  the 
shaft  of  the  fibula  (lying  posterior  to  the  peroneus  brevis), 
from  the  intermuscular  septa  on  either  side,  and  from  the 
inner  surface  of  the  deep  fascia  in  its  upper  third. 

Insertion  (see  Foot). — The  tendon  of  the  muscle  runs 
behind  the  external  malleolus  (having  the  tendon  of  the 
peroneus  brevis  in  front),  in  front  of  the  peroneal  tubercle 
on  the  OS  calcis,  through  the  groove  in  the  cuboid,  across 
the  foot  to  the  base  of  the  first  metatarsal  bone  and  the 
internal  cuneiform. 

Behind  the  malleolus  the  two  tendons  have  a  common 
synovial  sheath,  in  the  sole  the  long  tendon  has  a  special 
one.  A  sesamoid  bone  is  often  found  in  the  tendon  as  it 
crosses  the  cuboid  bone. 

Nerve  Supply. — The  musculocutaneous  which  passes 
through  the  muscle. 

Action. — To  extend  the  foot  on  the  leg,  to  abduct  the 
fore  part  of  the  foot,  to  depress  the  ball  of  the  great  toe 
(inner  border  of  the  foot)  and  raise  the  outer  border  of  the 
foot  (producing  eversion  of  the  sole).  It  is  an  important 
factor  in  maintaining  the  anteroposterior  and  transverse 
arches  of  the  foot  and  in  walking. 

Peroneus  Brevis.     Figs.  123,  124. 

Origin. — From  the  lower  two-thirds  of  the  outer  surface 
of  the  fibula,  overlapping  the  peroneus  longus  for  its  lower 


THE  LOWER  EXTREMITY,  POSTERIOR.  681 

third.      From  the  intermuscular  septa  and  deep  fascia  of  the 

Insertion  (see  Dorsum  of  Foot). — Into  the  prominent 
base  of  the  fifth  metatarsal  bone.  The  tendon  of  the 
muscle  Hes  in  front  of  that  for  the  peroneus  longus  ; 
as  the  two  pass  behind  the  external  malleolus,  one  synovial 
sheath  here  encloses  them  both. 

Nerve  Supply. — The  musculocutaneous. 

Action. — To  extend  the  foot,  to  abduct  the  foot,  to  raise 
the  outer  border  of  the  foot.  In  all  its  actions  it  is  much 
inferior  to  the  peroneus  longus. 

The  Posterior  Tibial  Nerve.      Figs.  128,  130,  13 1. 

This  is  the  continuation  of  the  internal  popliteal  nerve 
from  the  lower  border  of  the  popliteus  muscle  to  the  mid- 
point between  the  internal  malleolus  and  the  point  of  the 
heel,  where  it  terminates  by  dividing  into  the  external  and 
internal  plantar  nerves. 

The  posterior  tibial  nerve  lies  first  at  the  inner  side  of  the 
corresponding  artery,  but  crosses  behind  the  artery  (just 
after  -the  peroneal  branch  is  given  off)  to  the  outer  side, 
which  position  it  keeps  for  the  rest  of  its  course. 

Branches. — (i)  Muscular  to  the  tibialis  posticus,  flexor 
longus  digitorum,  and  flexor  longus  hallucis.  (2)  Articu- 
lar, one  or  more  filaments  to  the  ankle  joint.  (3)  Cuta- 
neous, internal  calcanean  (calcaneoplantar).  Pierces  the 
internal  annular  ligament  and  supplies  the  integument  over 
the  inner  side  of  the  heel,  and  back  part  of  the  sole. 

The  Anterior  Tibial  Artery.      See  page  593. 

The  Posterior  Tibial  Artery.      Figs.  130,  131. 

This  is  the  continuation  of  the  popliteal,  of  which  it  is 
the  larger  terminal  branch,  from   the   lower  border  of  the 


632  A  MANUAL   OF  ANA  TOMY. 

popliteus  muscle  to  the  point  mid-way  between  the  internal 
malleolus  and  the  point  of  the  heel,  at  which  place  it  divides 
into  the  internal  and  external  plantar  vessels. 

The  artery  is  covered  by  the  skin,  superficial  and  deep 
fascia,  the  gastrocnemius  and  soleus  muscles,  and  the  deep 
intermuscular  fascia  of  the  leg.  The  muscular  covering  is 
wanting  in  the  lower  third  of  its  course. 

The  artery  crosses  the  posterior  surface  of  the  tibialis 
posticus,  flexor  longus  digitorum,  tibia,  and  the  internal 
lateral  ligament  of  the  ankle  joint.  At  the  ankle  the  artery 
is  covered  by  the  annular  ligament  and  origin  of  the  abduc- 
tor hallucis  muscle. 

The  arteiy  has  an  accompanying  vein  upon  either  side 
which  frequently  communicate  by  cross  branches.  The 
posterior  tibial  nerve  is  at  its  beginning  at  the  inner  side  of 
the  artery,  but  crosses  it  where  the  peroneal  artery  arises, 
and  continues  at  the  outer  side  of  the  artery  for  the  rest  of 
its  course. 

Behind  the  internal  malleolus  the  posterior  tibial  artery 
is  the  central  structure  of  five  others. 

From  before  backward  the  order  is,  tendon  of  the  tibialis 
posticus,  tendon  of  the  flexor  longus  digitorum,  artery, 
posterior  tibial  nerve,  and  (at  a  little  distance,  and  on  a 
deeper  plane)  the  tendon  of  the  flexor  longus  hallucis. 
Besides  these  the  venae  comites  lie,  one  in  front  the  other 
behind  the  artery  and  next  to  it. 

Brandies. — (i)  Muscular,  numerous  to  the  surrounding 
muscles.  (2)  The  nutrient  artery  of  the  tibia,  largest  in 
the  body,  arises  near  the  beginning  of  the  posterior  tibial, 
and  enters  the  nutrient  foramen  at  the  upper  and  middle 
thirds  of  the  outer  border  of  the  tibia.  (3)  Cutaneous  (two 
or  three),  which  reach  the  inner  side  of  the  leg  betv/een  the 
superficial  and  deep  sets  of  muscles.      (4)  A  communicating 


THE  LOWER  EXTREMITY,  POSTERIOR.  633 

branch  to  the  peroneal  under  the  tendon  of  the  flexor 
longus  halhicis,  and  about  an  inch  above  the  ankle  joint. 
(5)  One  or  more  small  internal  malleolar  branches  to  the 
inner  side  of  the  ankle.  (6)  The  artery  below,  which  is 
its  largest  branch. 

The  Peroneal  Artery.      Figs.  125,  130. 

This  is  a  branch  from  the  posterior  tibial,  about  an  inch 
below  the  lower  border  of  the  popliteus  muscle  ;  it  turns 
outward  and  downward  along  the  fibular  side  of  the  leg, 
lying  deeply  placed  between  the  tibialis  posticus  and  flexor 
longus  hallucis,  or  else  under  the  latter.  About  three 
inches  above  the  ankle  joint  it  gives  off  the  anterior  pero- 
neal and  then  continues  under  the  name  of  the  posterior 
peroneal  to  behind  the  external  malleolus,  where  it  breaks 
up  into  several  terminal  branches  to  the  outer  and  back 
part  of  the  os  calcis.  There  are  two  accompanying  veins. 
Brajtchcs  of  the  Peroneal  Artery. 

(i)  Muscular  branches  to  the  adjacent  muscles.  (2)  A 
7iutrient  artery  to  the  fibula,  in  the  middle  and  lower  thirds 
•of  the  leg.  (3)  The  anterior  pcro7ieal.  This  artery  is 
given  off  about  three  inches  above  the  ankle  joint,  passes 
forward  between  the  tibia  and  fibula  and  through  the  inter- 
osseous membrane  to  the  front  of  the  leg,  then  turns  down- 
ward to  supply  the  outer  part  of  the  front  of  the  ankle. 
See  page  594.  (4)  The  communicating  branch  (or 
branches),  anastomoses  with  the  posterior  tibial  across 
the  lower  end  of  the  tibia.  See  Posterior  Tibial.  (5)  The 
cutaneous  branches  to  the  integument  upon  the  outer  side 
of  the  leg.  (6)  The  external  calcanean,  supplies  the  parts 
at  the  outer  side  of  the  os  calcis.  This  with  the  small 
terminal  branches  of  the  peroneal  anastomose  about  the 
ankle  with  the  external  malleolar,  anterior  peroneal,  tarsal 


634  A  MANUAL  OF  ANA  TOMY. 

(on  outer  side)  and  with  the  posterior  tibial  and  internal 
calcanean  branch  of  the  external  plantar  (on  the  inner  side). 

DISSECTION. 

No  incision  through  or  around  the  sole  is  necessary. 

Working  from  the  heel  forward,  dissect  the  skin  off  in  one  piece  to  the 
sides  of  the  sole  and  toes  (where  its  removal  was  stopped  when  on  the  dorsum 
of  the  foot) . 

Cut  away  the  entire  flap. 

The  supe7-ficial  fascia  will  be  found  as  a  thick  pad  of  fatty  and  connective 
tissue  covering  the  sole. 

It  is  to  be  entirely  removed  so  as  to  thoroughly  expose  the  deep  fascia. 
For  this  purpose  the  curved  scissors  will  be  found  to  be  the  most  useful. 

Be  careful  to  save  the  digital  nerves  which  lie  imbedded  in  the  fat  between 
the  processes  of  the  plantar  fascia. 

The  Superficial  Fascia,  or  the  subcutaneous  tissue. 

This  layer  is  much  thickened  in  the  foot  to  form  pads  at 
the  bearing  points  of  the  sole  for  the  protection  of  the 
deeper  parts.  These  pads  are  found  at  the  heel,  ball  of 
the  foot  and  toes,  and  are  seen  to  be  composed  of  a  coarse 
meshed  framework  of  connective  tissue  filled  with  fat. 

The  Plantar  Fascia,      Fig.  132. 

This  is  the  specialized  portion  of  the  deep  fascia  of  the 
foot  which  preserves  its  shape  and  protects  its  deeper  parts. 
It  covers  the  entire  sole  of  the  foot,  but  the  central  portion 
is  much  stronger  and  thicker  than  the  lateral  portions. 

The  middle  portion  of  the  plantar  fascia  is  narrow  behind 
where  it  is  attached  to  the  under  surface  of  the  back  part 
of  the  OS  calcis,  and  widens  out  as  it  passes  forward  to  the 
fore  part  of  the  foot  where  at  the  base  of  the  toes  it  divides 
into  five  slips,  one  for  each  toe.  Each  slip  passes  for- 
ward, splits  to  enclose  the  tendons  of  the  long  and  short 
flexor  muscles  of  the  toes,  and  is  inserted  into  the  lateral 
ligaments  of  the  metatarsophalangeal  articulation,  and  the 
deep  transverse  ligament  of  the  heads  of  the  tarsal  bones. 


Fig.  132.  Dissection  of  the  Foot,  Plantar  Surface.— i,  Middle  or  central 
portion  of  plantar  fascia.  2,  Internal  and  3,  External  portions.  4,  The  digital  nerves 
(raised  on  a  small  rod). 


636  A  MANUAL   OF  ANATOMY. 

Between  these  fasciculi  pass  the  lumbricales  and  interossei 
muscles  and  the  digital  vessels  and  nerves. 

The  central  portion  of  the  plantar  fascia  is  connected  at 
its  margins  to  the  ligaments  which  cover  the  under  surface 
of  the  bones  of  the  foot,  by  fibrous  septa,  the  external  and 
internal  intermuscular  septa  ;  these  divide  the  foot  into  three 
compartments. 

The  lateral  portions  of  the  fascia  are  continuous  with  the 
margins  of  the  central  portion  and  pass  into  the  deep  fascia 
covering  the  dorsum  of  the  foot  and  the  lateral  annular  liga- 
ments of  the  ankle.  In  addition  the  external  portion  has  a 
strong  band  which  extends  from  the  outer  surface  of  the 
OS  calcis  and  the  external  annular  ligament,  and  is  attached 
to  the  base  of  the  fifth  metatarsal  bone,  and  the  internal 
portion  passes  from  the  inner  side  of  the  os  calcis  and  inter- 
nal annular  ligament  forward,  to  be  inserted  into  the  base 
of  the  first  phalanx  of  the  great  toe. 

DISSECTION. 
Remove  the  plantar  fascia  by  cutting  away  altogether  the  outer  and  inner 
portions.  Incise  the  central  part  transversely  about  three  inches  from  the 
heel,  raise  the  anterior  portion  from  the  muscle  beneath  and  carefully  dissect 
it  forward,  dividing  the  strong  intermuscular  septum  on  each  side  of  the  mus- 
cle, until  the  insertions  of  the  fasciculi  are  reached.  Stop  here  to  examine 
how  the  flexor  tendons  pass  through  the  divided  fasciculi  while  the  digital 
nerves,  vessels,  and  lumbrical  muscles  lie  between  the  fasciculi  themselves, 
then  remove  the  fascia  entirely.  Leave  the  posterior  portion  attached  to  the 
muscle. 

The  First  Layer. 

The  Flexor  Brevis  Digitorum.     Fig.  133. 

Origin. — From  the  anterior  part  of  the  greater  (inner) 
tubercle  of  the  os  calcis,  from  the  deep  surface  of  the 
middle  portion  of  the  plantar  fascia  for  its  posterior  third, 
and  from  the  sides  of  the  intermuscular  septa. 


THE  LOWER  EXTREMITY,  POSTERIOR.  637 

Insertion. — By  four  tendons  into  the  bases  of  the  second 
phalanges  of  the  four  smaller  toes.  The  tendons  of  the 
brevis  divide  for  the  passage  of  the  tendons  of  the  flexor 
longus  digitorum,  then  reunite,  forming  a  buttonhole  for 
the  passage  of  the  tendons  of  the  flexor  longus  digitorum, 
they  then  again  divide  and  pass  to  their  insertion  into  the 
bases  of  the  second  phalanges. 

Nerve  Supply. — The  internal  plantar. 

Action. — To  flex  the  four  outer  toes,  beginning  at  the 
second  phalanges,  to  flex  the  bones  of  the  foot  and  pre- 
serve the  arch. 

Abductor  Hallucis  (Pollicis).      Fig.  133. 

Origin. — From  the  inner  margin  of  the  greater  tubercle 
of  the  OS  calcis,  the  deep  part  of  the  internal  annular  liga- 
ment, the  side  of  the  intermuscular  septum,  and  from  the 
deep  surface  of  the  plantar  fascia  covering  it. 

Insertion. — Into  the  inner  margin  of  the  base  of  the  first 
phalanx  of  the  great  toe. 

The  tendon  of  this  muscle  is  joined  before  its  insertion 
by  the  inner  half  of  the  tendon  of  the  flexor  brevis  hallucis. 

Beneath  the  origin  of  the  muscle  is  a  fibrous  arch  which 
reaches  from  the  internal  intermuscular  septum  to  the  deep 
ligamentous  structures  at  the  inner  border  of  the  foot,  and 
through  which  pass  the  plantar  vessels  and  nerves. 

Nerve  Supply. — The  internal  plantar. 

Action. — To  abduct  the  great  toe  from  the  middle  line 
of  the  foot  (passes  through  the  middle  of  the  second  toe), 
to  flex  the  first  phalanx  of  the  great  toe,  to  preserve  the 
arch  of  the  foot. 

Abductor  Minimi  Dig-iti.      Fig.  133. 
Origin. — From  the  under  surface  of  the  os  calcis  in  front 
of  both  tuberosities,  from  the  side  of  the  external  intermus- 


638  A  MANUAL  OF  ANATOMY. 

cular  septum,  and  from  the  deep  surface  of  the  band  reach- 
ing from  the  outer  side  of  the  os  calcis  (the  lesser  tuberos- 
ity) to  the  base  of  the  fifth  metatarsal  bone. 

Insertion. — The  outer  side  of  the  base  of  the  first  phalanx 
of  the  little  toe,  the  outer  side  of  the  base  of  the  fifth  meta- 
tarsal bone. 

Nerve  Supply. — The  external  plantar. 

Action. — To  abduct  the  httle  toe  from  the  middle  line  of 
the  foot,  to  flex  the  first  phalanx  of  the  little  toe.  (Abduc- 
tion of  the  first  phalanx  carries  with  it  the  rest  of  the  pha- 
langes, but  flexion  is  only  of  the  first  phalanx). 

The  Internal  Plantar  Nerve.     Figs.  132,  133. 

This  is  larger  than  the  external  plantar.  It  is  accom- 
panied by  the  corresponding  artery  for  a  part  of  its  course. 

It  runs  forward  between  the  abductor  hallucis  and  the 
flexor  brevis  digitorum  muscles  and  ends  at  the  middle  of 
the  foot  by  dividing  into  three  (or  four)  digital  branches. 
These  are  named  from  within  outward. 

(i)  The  first  digital  branch  supplies  a  muscular  branch  to 
the  flexor  brevis  hallucis  and  cutaneous  branches  to  the 
inner  side  of  the  great  toe.  (2)  The  second  sends  a  mus- 
cular branch  to  the  first  lumbricalis,  then  bifurcates  to  sup- 
ply the  adjacent  sides  of  the  first  and  second  toes.  (3)  The 
third  supplies  the  second  lumbricalis,  and  the  contiguous 
sides  of  the  second  and  third  toes.  (4)  The  fourth  ;  this 
communicates  with  the  superficial  division  of  the  external 
plantar  nerve,  and  supplies  the  opposite  sides  of  the  third 
and  fourth  toes.  The  digital  nerves  supply  the  joints  of 
the  toes  which  they  pass  over.  Their  branches  to  the  toes 
after  their  bifurcation  are  called  collateral  digital  nerves. 
There  are  six  digital  and  ten  collateral  digital  nerves,  the 
internal    plantar   furnishing  four  of  the  digital  and  seven 


F'g-  *33'  Dissection  of  Foot,  Plantar  Surface.— i,  i,  i,  Abductor  hallu- 
cis  removed.  2,  Tendon  of  flexor  longus  hallucis.  3,  Tendon  of  flexor  longus  digi- 
torum.  4,  Flexor  accessorius.  5,  Internal  plantar  artery.  6,  Cut  end  of  internal 
plantar  nerve.  7,  7,  Abductor  minimi  digiti  removed.  8,  Lumbricales.  9.  Flexor 
brevis  minimi  digiti.  10,  Tendon  of  peroneus  longus.  11,  External  plantar  artery. 
12,  External  plantar  nerve.  13,  Long  inferior  calcaneocuboid  ligament.  14,  14,  14, 
Remains  of  flexor  brevis  digitorum. 


640  ^4  MAXUAL  OF  AXATOMY. 

collateral  digital  branches  ;  the  external  plantar  furnishes 
the  remainder,  two  digital  and  three  collateral  digital 
nerves.     These  are  numbered  from  luithiu  outward. 

The  Internal  Plantar  Artery.      Figs.  133,  134. 

The  smaller  branch  of  the  posterior  tibial  behind  the 
internal  malleolus.  Its  course  is  forward  and  slightly  out- 
ward, under  cover  of  the  abductor  hallucis  muscle,  the'n 
between  this  muscle  and  the  flexor  brevis  digitorum,  to  the 
ball  of  the  great  toe  where  it  terminates  in  branches  which 
anastomose  with  the  fifth  and  sixth  plantar  digital  arteries. 

The  Branches  of  the  Internal  Plantar  Artery, 
(i)  [Muscular,  to  the  adjacent  muscles.  (2)  Cutaneous, 
to  the  integument  of  the  inner  segment  of  the  sole.  (3) 
Anastomotic,  beneath  the  abductor  hallucis  to  the  inner 
side  of  the  foot  to  anastomose  with  the  internal  malleolar 
and  internal  tarsal  arteries  of  the  dorsum  of  the  foot.  (4) 
Superficial  digital,  small  branches  which  pass  forward  in 
the  inner  three  interosseous  spaces  with  the  digital  branches 
of  the  internal  plantar  nerve,  and  anastomose  with  the 
digital  arteries. 

DISSECTION. 

Section  the  internal  plantar  nen-e  where  it  appears  in  the  sole.  Divide  the 
abductor  muscles  about  one  inch  in  front  of  their  origin,  and  the  flexor  brevis 
digitorum  transversely  across  at  its  middle. 

Reflect  the  parts. 

The  Second  Layer. 

Flexor  Accessorius.      Fig,  133, 

Origin. — The  internal,  larger,  head,  from  the  inner  sur- 
face of  the  OS  calcis.  The  external,  smaller,  head  from 
the  outer  margin  of  the  os  calcis  in  front  of  the  external 
tuberosity,  and  from  the  long  plantar  ligament. 


THE  LOWER  EXTREMITY,  POSTERIOR.  641 

Insertion. — Into  the  outer  margin  and  upper  surface  of 
the  tendon,  of  the  flexor  longus  digitorum. 

Nerve  Supply. — The  external  plantar. 

Action. — To  convert  the  oblique  pull  of  the  flexor 
long"us  digitorum  into  a  direct  one,  and  thus  assist  in  flex- 
ing  the  four  outer  toes.  Acting  alone,  or  when  the  flexor 
longus  digitorum  is  blocked  by  the  full  extension  of  the 
ankle,  it  will  still  flex  the  toes. 

The  Lumbricales.     Four  in  number.     Fig.  133. 

Origin. — Arise  from  the  clefts  between  the  tendons  of 
the  flexor  longus  digitorum  (being  attached  to  two  adja- 
cent tendons  excepting  the  most  internal,  which  arises  from 
the  inner  margin  of  the  internal  tendon). 

Insertion. — Into  the  aponeurotic  expansion  of  the  tendon 
of  the  extensor  longus  digitorum  at  the  inner  side  of  the 
four  outer  toes. 

Xcrve  Supply. — The  two  (sometimes  only  one)  inner 
muscles  are  supplied  by  the  internal  plantar,  the  two 
(sometimes  three)  outer  are  supplied  by  the  external 
plantar. 

Action. — These  muscles  will  flex  the  first  set  of  pha- 
langes (as  their  tendons  pass  hcloiv  the  centre  of  motion  of 
the  metatarsophalangeal  articulations),  and  extend  the  last 
two  sets  of  phalanges  (because  their  tendons  are  inserted 
into  the  tendons  of  the  long  extensor  muscle  above  the 
centre  of  motion  of  these  articulations).  Besides  this 
common  action,  the  internal  one  will  abduct  the  second 
toe,  and  the  rest  adduct  the  three  outer  toes  with  reference 
to  the  middle  line  of  the  foot  (which  passes  through  the 
centre  of  the  second  toe). 

For  the   tendons  of  the  flexor  longus  hallucis  and  the 
flexor  longus  digitorum,  see  these  muscles,  page  627. 
41 


642  A  MANUAL   OF  ANATOMY. 

The  External  Plantar  Nerve.      Figs.  133,  134. 

This  is  the  outer  branch  into  which  the  posterior  tibial 
divides  behind  the  internal  malleolus.  The  nerve  (with  the 
external  plantar  artery)  runs  forward  and  outward  between 
the  flexor  brevis  digitorum  and  the  flexor  accessorius,  and 
divides  into  two  branches  at  the  base  of  the  fifth  metatarsal 
bone,  the  superficial  and  deep. 

Before  this  division  the  nerve  supplies  muscular  branches 
to  the  flexor  accessorius  and  the  abductor  minimi  digiti, 
and  cutaneous  twigs  to  the  outer  border  of  the  sole  of  the 
foot. 

The  superficial  branch.  This  supplies  muscular  branches 
to  the  interossei  in  the  space  between  the  fourth  and  fifth 
toes,  and  the  flexor  brevis  minimi  digiti,  a  communicating 
branch  to  the  internal  plantar,  and  digital  branches  to  the 
adjacent  one  and  one-half  outer  toes  (adjacent  side  of  the 
fourth  and  fifth,  and   outer  side  of  the  latter). 

The  deep  brancli.  This  accompanies  the  external  plantar 
artery  into  the  deep  parts  of  the  foot.  It  supplies  the  two 
(sometimes  three)  outer  lumbricales,  adductor  hallucis, 
transversus  pedis,  and  the  rest  of  the  interossei  (those  in  the 
three  inner  spaces). 

The  External  Plantar  Artery.      Figs.  133,  134. 

This  is  the  larger  branch  into  which  the  posterior  tibial 
divides  behind  the  internal  malleolus.  The  artery  passes 
forward  and  outward,  being  covered  by  the  abductor  hallu- 
cis and  the  flexor  brevis  digitorum,  to  the  outer  segment 
of  the  foot  until  it  reaches  the  base  of  the  fifth  metatarsal 
bone,  where  it  turns  short  inward,  passing  deeply  between 
the  interossei  muscles  and  the  lumbricales  and  flexor  ten- 
dons, and  terminates  at  the  posterior  part  of  the  space  be- 
tween the  first  and  second  metatarsal  bones  where  it  forms 


THE  LOWER  EXTREMITY,  POSTERIOR.  643 

a  junction  with  the  communicating  branch  of  the  dorsal 
pedis  and  so  completes  the  plantar  arch.  The  artery  is 
accompanied  by  two  venae  comites  and  the  external  plantar 
nerve. 

Brandies  of  the  External  Plantar  Artery. 

(i)  Muscular,  numerous  small  branches  to  the  near-by 
muscles. 

(2)  Calcanean  (internal),  two  or  three  branches  to  the 
inner  side  of  the  os  calcis. 

(3)  Cutaneous,  to  the  integument  along  the  outer  border 
of  the  sole. 

(4)  Anastomotic,  pass  over  the  outer  border  of  the  foot 
to  anastomose  with  the  external  malleolar,  tarsal  and  meta- 
tarsal branches  upon  the  dorsum  of  the  foot. 

All  these  branches  come  off  the  artery  before  it  turns 
inward  to  form  the  plantar  arch. 

From  the  plantar  arch  arise  the  following  : 

(5)  Articular,  pass  backward  to  the  joints  of  the  tarsus. 

(6)  Posterior  perforating,  three,  which  ascend  through 
the  back  part  of  the  three  outer  interosseous  spaces  and 
anastomose  on  the  dorsum  of  the  foot  with  the  dorsal  in- 
terosseous arteries  (branches  of  the  metatarsal  artery.  See 
page  596). 

(7)  Digital  branches.  Four  in  number  ;  arise  from  the 
front  of  the  arch,  [a)  The  first  digital,  from  the  beginning 
of  the  arch  at  the  base  of  the  fifth  metatarsal  bone,  to  the 
outer  side  of  the  little  toe,  crossing  in  its  course  the  flexor 
brevis,  and  the  adductor  minimi  digiti  muscles.  (^)  (<r) 
and  id')  The  second,  third,  and  fourth  digital  arteries 
pass  forward  upon  the  interossei  muscles  through  the  mid- 
dle of  the  fourth,  third  and  second  interosseous  spaces  to 
the  web  of  the  toes  where  each  divides  into  two  collateral 
digital  branches  to  the  adjacent  sides  of  the  toes,      {e')  (/) 


644  A  MANUAL  OF  ANA  TOMY. 

The  fifth  and  sixth  digital  arteries  are  both  branches  of  the 
communicating  artery  from  the  dorsum  of  the  foot.  The 
sixth  suppHes  the  inner  side  of  the  great  toe  and  anasto- 
moses backward  with  the  internal  plantar  artery ;  the  fifth 
takes  a  forward  course  like  the  other  digital  arteries,  di- 
vides into  two  collateral  digital  branches  at  the  web  of  the 
toes  and  supplies  the  opposing  sides  of  the  great  and  second 
toes. 

There  are  then  six  digital,  and  ten  collateral  digital  ar- 
teries, numbered  from  without  inward. 

DISSECTION. 
Divide  tlie  tendon  of  the  flexor  longus  digitorum  just  in  front  of  the  acces- 
sorius  and  reflect  it,  with  the  lumbricales,  forward. 
Clean  all  the  remaining  muscles  and  tendons. 

The  Third  Layer. 

Plexor  Brevis  Hallucis  (PoUicis).     Fig.  134. 

Origin. — From  the  inner  border  of  the  cuboid  bone,  from 
the  under  surface  of  the  tendon  of  the  tibiahs  posticus,  over 
the  cuneiform  bones. 

Insertion. — By  a  divided  tendon,  one  part  with  the  ab- 
ductor hallucis  into  the  inner  border  of  the  base  of  the  first 
phalanx,  the  other  with  the  tendon  of  the  adductor  hallu- 
cis into  the  outer  border  of  the  same  bone.  A  sesamoid 
bone  is  found  in  each  head. 

Nerve  Supply. — The  internal  plantar. 

Actio7i. — To  flex  the  first  phalanx  of  the  great  toe. 

The  Adductor  Hallucis.      Fig.  134. 

Origin. — From  the  plantar  surface  of  the  bases  of  the 
second,  third,  and  fourth  metatarsal  bones,  and  from  the 
sheath  of  the  tendon  of  the  peroneus  longus. 

Insertion. — Alone  with   the  outer   head  of    the    flexor 


Fig.  134.  Dissection  of  Foot,  Plantar  Surface.— i,  Cut  tendon  of  flexor 
longus  hallucis.  2,  Transversus  pedis.  3,  Adductor  hallucis.  4,  Abductor  hallucis 
(end  of  tendon).  5,  Flexor  brevis  hallucis.  6,  Internal  plantar  artery.  7,  Cut  tendon 
of  flexor  longus  digitorum.  8,  Cut  tendon  of  flexor  longus  hallucis.  9,  Cut  end  of 
internal  plantar  nerve.  lo,  10,  Cut  ends  of  abductor  minimi  digiti.  11,  Flexor  brevis 
minimi  digiti.  12,  Tendon  of  peroneus  longus.  13,  Long  inferior  calcaneocuboid 
ligament.  14,  External  plantar  artery,  plantar  arch  and  branches.  15,  External 
plantar  nerve. 


646,  A  MANUAL  OF  ANATOMY. 

brevis  hallucis  into  the  outer  surface  of  the  base  of  the 
first  phalanx  of  the  great  toe. 

Nerve  Supply. — The  external  plantar  nerve. 

Action. — To  adduct  and  flex  the  first  phalanx  of  the 
great  toe. 

Transversus  Pedis.     Fig.  134. 

Origin. — From  the  under  surface  of  the  three  outer  me- 
tatarsophalangeal articulations,  and  from  the  deep  trans- 
verse metatarsal  hgaments. 

Insertio7i. — In  common  with  the  adductor  hallucis,  see 
above. 

Nerve  Supply. — The  external  plantar. 

Action. — To  adduct  the  first  phalanx  of  the  great  toe,  to- 
draw  the  metatarsal  bones  together. 

Plexor  Brevis  Minimi  Digiti.     Fig.  133. 

Ongin. — From  the  under  surface  of  the  base  of  the  fifth 
metatarsal  bone  and  from  the  sheath  of  the  tendon  of  the 
peroneus  longus  muscle.  Into  the  outer  part  of  the  base 
of  the  first  phalanx  of  the  little  toe. 

Nerve  Supply. — The  external  plantar. 

Action. — To  flex  and  abduct  (feebly)  the  first  phalanx  of 
the  little  toe. 

The  Pourth  Layer. 

Plantar  Interossei. — Three  in  number.  (Dorsal,  four, 
see  page  592.)     Fig.  134. 

Origin. — From  the  under  and  inner  surface  of  the  three 
outer  metatarsal  bones. 

Insertion. — Slightly  into  the  inner  portion  of  the  base  of 
the  first  phalanges  of  the  third,  fourth,  and  fifth  toes,  and 
more  especially  into  the  inner  margin  of  the  aponeurotic 
expansion  of  the  tendon  of  the  extensor  longus  digitorum 
at  the  back  of  the  first  phalanges  of  the  above  toes. 


THE  LOWER  EXTREMITY,  POSTERIOR.  647 

Nerve  Supply. — The  external  plantar. 

Aetion. — These  muscles  have  the  action  common  to  the 
dorsal  interossei  and  the  lumbricales,  of  flexing  the  first 
set  of  phalanges  and  extending  the  rest ;  their  special 
action  is  to  adduct  the  first  phalanges  of  the  three  outer 
toes  to  the  middle  line  running  through  the  second  toe. 

DISSECTION. 

The  tendons  of  the  peroneus  longus,  and  tibialis  posticus  remain  to  be  dis- 
sected.    For  these  muscles  see  pages  630  and  628. 


ADDENDUM. 


Pronator  Quadratus. 

Origin. — From  the  antero-internal  surface  of  the  ulna 
for  its  lower  one-fourth. 

Insertion. — Into  the  anterior  surface  and  outer  border  of 
the  radius  for  its  lower  one-fourth. 

Nerve  Supply. — The  anterior  interosseous  (median). 

Action. — To  pronate  the  forearm. 

The  Axillary  Space. — This  is  an  irregularly-shaped  pyra- 
mid, with  the  following  boundaries  : — 

Anteriorly,  the  clavicle ;  the  subclavius,  pectoralis  major 
and  minor  muscles  ;  the  costocoracoid  membrane  ;  the  pec- 
toral and  clavipectoral  fascise  (the  latter  an  extension  of 
the  costocoracoid  membrane). 

Posteriorly,  the  subscapularis,  teres  major,  and  latissimus 
dorsi  muscles. 

Internally,  the  serratus  magnus  muscle  ;  portions  of  the 
first  to  the  fourth  ribs  inclusive,  with  the  intervening  mus- 
cles and  fascia. 

Externally,  the  upper  portion  of  the  humerus ;  long 
head  of  the  biceps  and  the  coracobrachiaHs. 

The  apex  is  between  the  clavicle  and  first  rib,  and  is 
occupied  by  the  brachial  plexus  and  large  blood  vessels. 

The  base  is  formed  by  the  axillary  fascia. 

The  average  weight  of  the  adult  human  brain  is,  for 
males,  49^  ounces  ;  for  females,  44  ounces. 


648 


NDEX. 


Abdomen,  boundaries  of,  432 

dissection  of,  435 

exterior  of,  432 

interior  of,  462 

dissection  of,  473 

landmarks  of,  432 

subcutaneous  nerves  of,  436 

superficial  fascia  of,  436 

lymphatics  of  (inguinal),  436 
veins  of,  436 
Abdominal  aorta,  515 
dissection  of,  515 

cavity,  432 

muscles,  nerve  supply  for,  453 

regions,  435 

ring,  external,  444 
internal,  456 

rings,  formation  of,  457 

viscera,  covered  by  peritoneum,  4S2 
seen   on   opening  the  abdomen,  479, 
48 1,  489 
Abducens  nerve  (sixth  cranial),  57,  201 
Abductor  hallucis,  637 

minimi  digit! ,  306,  637 

pollicis,  306 
Abscess,  cervical,  141 

psoas,  525 

retropharyngeal,  141 
Accelerator  urina;,  410 
Accessorius,  375 
Achillis,  tendo-,  622 
Acromial  artery,  272,  278 

nerves,  76,  91 
Acromioclavicular  joint,  256 
Acromion  process,  256 
Acromiothoracic    artery    and    branches, 

272,  27S 
Action  of  muscles  on  vocal  cords,  147 
Adam's  apple,  (39 
Adductor  brevis,  576 

hallucis,  644 

longus,  566 

magnus,  57S 

(obliquus)  pollicis,  308 

(transversus)  pollicis,  308 
Afterbrain,  169,  171,  175 
Ala  cinerea,  252 
Alcock's  canal,  399,  411 
Alimentary  canal,  development,  462 
Ampulla  of  vas  deferens,  542 
Amygdaloid  lobe  of  cerebellum,  242 

nucleus,  236 
Anal  fascia,  402 
Anastomosis  about  the  elbow,  387 

about  the  knee,  624,  626 

"  crucial,"  580,  614 


Anastomotica  magna  (brachial),  287 
(femoral),  deep  branch,  573 
superficial  branch,  557 
Anatomical  "  points,"  599 

"  canals,"  446,  599 

"rings,"  446,  599 
Anconeus,  3S1 
Angle  of  penis,  440 
Angular  artery,  65 

convolution  (or  gyrus),  187 

process  of  frontal  bone,  external,  18 
internal,  18 
Ankle,  annular  ligaments  of,  anterior,  584 
external,  585 
internal,  586 
Annular  ligament  of  wrist,  anterior,  302 

posterior,  37S 
Annulus  ovalis,  355 
Ansa  hypoglossi,  88 
Anterior  crural  nerve,  532,  557,  568 
muscular  branches  of,  56S 

temporal  artery,  26 

tibial  artery  and  branches,  593,  594 

triangles  of  neck,  82 
Anterolateral  ganglionic   arterial  group, 

162 
Anteromedian  ganglionic  arterial  group, 

162 
Antrum  of  Highmore,  opening  of,  148 
Anus,  406 
Aorta,  334 

abdominal,  515 

arch  of,  334 

ascending,  334 

descending,  338 

thoracic,  338 
branches  of,  345 

transverse,  336 
Aperture  of  Eustachian  tube,  141,  145 

of  larynx,  145 

of  mouth,  141 

of  nares,  141 

of  thorax  (superior),  323 
Apex  of  heart,  260 

of  lung,  262 
Aponeurosis  of  external  oblique  (abdo- 
men), 444 

lumbar,  451 

of  occipitofrontalis,  25 

pharyngeal,  124 

transversalis,  454 

vertebral,  373 
Appendices  epiploicse,  500 
Appendix,  auricular,  354,  355 

ensiform,  255.  432 

vermiform,  476,  500 


649 


650 


INDEX. 


Aqueduct  of  Sylvius,  171,  240 

development  of,  175 
Arachnoid,  Ij'mphatics  of,  156 
membrane,  154 
nerves  of,  156 
removal  of,  156 
septum,  392 
spinal,  390 
Arachnoidal  villi,  155 
Arantius,  corpus  of,  nodules,  355 
Arbor  vitae  (cerebellum),  244 
Arch  of  aorta,  334 
palmar,  deep,  310,  and  superficial,  303 
plantar,  643 
supra-orbital,  18 
zygomatic,  18 
Arches  of  fauces,  anterior  and  posterior, 
142 
palatine,  anterior  and  posterior,  142 
Arciform  fibers  or  tract,  external,  248,  254 
Areola,  nipple  (mammary  gland),  266 
Arm  and  forearm,  deep  fascia  of,  2S3 
dissection  of,  anterior,  282 

posterior,  360 
landmarks  of,  255  to  25b 
superficial,  264,  282 
nerves  of,  2S3,  365,  37S 
veins  of,  2S2,  378 
Arrangement  of  peritoneum,  473 
Artery  or  arteries  : — • 
abdominal  aorta,  515 
acromial,  272,  278 

acromiothoracic  and  branches,  272,  278 
alar  thoracic,  278 
anastomosis  about  the  elbow,  387 
knee,  626 
crucial,  580,  614 
anastomotica  magna  (brachial),  287 
(femoral),   deep,  573;   and   superfi- 
cial branch, 557 
angular,  65 
anterolateral  ganglionic  group  (brain), 

162 
anteromedian  ganglionic  group  (brain), 

162 
aorta,  334 

articular,  anterior  circumflex,  279 
azygos,  624 

of  external  plantar,  643 
of  internal  circumflex,  580 
of  interosseous  recurrent,  386 
of  popliteal,  624 
of  posterior  circumflex,  372 
of  sciatic,  613 

of  superior  profunda,  287,  372 
of  suprascapular,  371 
of  temporal,  62 
ascending  aorta,  334 
cervical,  in 
palatine,  95 
pharyngeal,  96 
auditory,  164 
auricular,  anterior,  62 
deep,  120 
posterior,  96 
axillary  and  branches,  275,  276 
azygos  articular,  624 
basilar,  158,  164 
branches,  164 
bicipital,  279 


Arterj'  or  arteries  : — 
brachial  and  branches,  286,  287 
bronchial,  345 
buccal,  104 
(facial),  64 

(internal  maxillar>-),  121 
to  bulb,  412 
calcanean,  external,  633 

internal,  643 
carotid,  common,  loi 
left,  340 
external,  92 
internal,  98,  158 
carpal,  anterior,  of  radial,  294 

of  ulnar,  297 
carpal,  posterior  of  radial,  387 

of  ulnar,  297,  388 
central,  of  retina,  53 
cerebellar,  inferior  and  superior,  164 
cerebral,  anterior,  15S,  163 
middle  (artery    of   cerebral    hemor- 
rhage), 160,  163 
posterior,  160,  164 
cervical,  ascending,  in 
of  cervix  of  uterus,  547 
deep  (profunda  cervicis),  113,  135 
superficial,  112,  130 
transverse,  112 
choroid,  anterior  and  posterior,  163 
ciliary,  53 

circle  of  Willis,  15S,  162 
circumflex  (axillary)  anterior,  278 
posterior,  279,  372 
femoral,  external,  579 

internal,  5S0 
iliac  deep,  519 
superficial,  557,  572 
clavicular,  272 
coccygeal,  613 
coeliac  axis,  509 
colica,    dextra,    media,    sinistra   (left, 

middle,  and  right),  512 
collateral  digital  of  fingers,  305,  388 

of  toes,  596,  643 
comes  nervi  ischiadic!,  613 

phrenici,  328 
communicating  cerebral,  anterior,  160 
posterior,  160 
dorsalis  pedis,  596 
of  palm,  304 
coronary,  inferior  (face),  64 
left  (heart),  353 
right  (heart),  352 
superior  (face),  65 
cortical  of  cerebral,  anterior,  163 
middle,  163 
posterior,  164 
cricothyroid,  93 
crucial  anastomosis,  5S0,  614 
of  crus  clitoridis,  426 

penis,  413 
cystic  (gall  bladder),  510 
deferential  to  vas,  547 
dental,  121,  122 
descending  aorta,  338 
digital  foot,  643 

collateral,  dorsal,  596 
plantar,  643 
hand,  304,  3SS 
collateral,  dorsal,  388 


INDEX. 


651 


Artery  or  arteries  : — 
digital  hand  collateral,  palmar,  305 
dorsal,  of  clitoris,  426 

of  penis,  deep,  412,  413 

superficial,  436,  573 

of  tongue  (lingual),  94 
dorsalis  hallucis,  596 

indicis,  3SS 

linguae,  94 

pedis,  595 

pollicis,  388 

scapulas,  278,  371 
epigastric,  deep,  454,  456 

superior,  321,  454 

superficial,  436,  557,  572 
epiploic,  511 
ethmoidal,  anterior  and  branches,  54,149 

posterior,  53,  149 
facial,  in  face  and  branches,  64 

in  necic  and  branches,  94 

transverse,  62 
femoral,  570 

branches,  572 

deep  (profunda  femoris),  579 
frontal,  26,  54 

ganglionic  arterial  groups  (brain),  an- 
terolateral,    anteromedian, 
posterolateral,   162,  and   pos- 
teromedian, 163 
gastric,  509 

gastroduodenalis,  510,  511 
gastro-epiploic,  left,  510 

right,  511 
gluteal,  548,  612 
hemorrhoidal,  inferior,  412 

middle,  547 

superior,  514 
hepatic,  510 
humeral,  272,  278 
hyoid  (lingual),  94 

(superior  thyroid),  93 
hypogastric  (obliterated),  538,  547 
ileocolic,  512 
iliac,  common,  518 

circumflex,  deep,  519 
superficial,  557,  572 

external,  519 

internal  and  branches,  546 
iliolumbar,  54S 
infra-orbital,  122 
innominate,  339 

intercostal,    anterior    (internal     mam- 
mary), 321 

aortic,  346 

superior,  346 
interossei  (hand),  dorsal,  388 
palmar,  310 

(foot),  dorsal,  595 
interosseous,  anterior,  296,  386 

common,  296 

posterior,  297,  385 

recurrent,  3S6 
labial,  inferior,  64 
lachrymal,  50,  53 
laryngeal,  inferior,  112 

superior,  93 
lateral  nasal,  65 

sacral,  548 
lenticulostriate  (cerebral  hemorrhage), 
162 


Artery  or  arteries : — 
lingual,  94 
lumbar,  518 

malleolar  branches  of  anterior  tibial, 
594 
of  posterior  tibial,  internal,  633 
mammary,  external,  279 

internal,  113,  320,  346 
masseteric  branches  of  facial,  64 

of  internal  maxillary,  121 
maxillary,  internal,  120 
median,  297 

meningeal    anterior,   small,    and    pos- 
terior, 44 

of  anterior  ethmoid,  44 

of  ascending  pharyngeal,  44 

of  occipital,  44 

of  posterior  eilimoid,  44 

middle,  121 

posterior,  96 

small,  121 

of  vertebral,  44 
mental  of  facial,  95 
mesenteric,  inferior,  512 

superior,  511 
metacarpal,  388 
metatarsal,  595 
musculophrenic,  321 
mylohyoid,  121 
nasal,  of  infra-orbital,  122 

of  anterior  ethmoidal,  54 

ophthalmic,  54 

of  sphenopalatine,  148 

lateral,  65 
nasopalatine,  122,  148 
nutrient  of  brachial,  287 
interosseous,  297 

of  femur,  third  perforating,  580 

of  fibula,  633 

of  humerus,  287 

of  ilium,  612 

of  radius,  297 

of  ulna,  297 

of  tibia,  632 
obliterated  hypogastrics,  538,  547 
obturator,  547,  583 
occipital,  95,  130 
oesophageal,  346 

of  bulb,  412 

of  cervix,  circular,  547 

of  crus  clitoridis,  426 

of  crus  penis,  413 

of  gastric,  509 

of  inferior  thyroid,  112 

of  larynx,  156 

of  phrenic,  516 
ophthalmic,  53 

branches  of,  26,  53 
orbital,  62 
ovarian,  518 
palatine,  ascending  or  inferior,  95 

superior,  122 
palmar  arch,  deep,  310 
superficial,  303 
interossei,  310 
palpebral,  54 

pancreatic,  from  hepatic,  510 
pancreatica  magna,  510 
pancreaticas  parvse,  510 
pancreaticoduodenalis,  inferior,  511 


652 


INDEX. 


Artery  or  arteries  : — 
pancreaticoduodenalis,  superior,  511 
parotid,  62 
perforating  of  deep  femoral,  5S0 

foot,  anterior  and  posterior,  596,  643 

hand,  anterior,  310 

internal  mammary,  321 

profunda  femurs,  5S0 
pericardial,  345 
perineal,  superficial,  412 

transverse,  412 
peroneal,  633 

anterior,  594 

posterior,  633 
pharyngeal,  ascending,  96 
phrenic,  inferior,  516 
plantar  arch,  643 

digital,  640,  643 
collateral,  643 

external,  642 

internal,  640 
pleural,  346 

popliteal  and  branches,  623,  624 
princeps  cervicis,  130 

pollicis,  310 
profunda  cervicis,  1 13,  130,  135 
inferior  (brachial),  287 
superior  (brachial),  287,  372 

femoris,  579 
pterygoid,  121 
pterygopalatine,  122 
pubic,  547 

pudic  internal,  411,  547 
in  female,  426 

deep  external,  573 

superficial  external,  557,  573 
pulmonary,  332 

left,  334 

right,  332 
pyloric,  510 

radial,  carpal,  anterior,  294 
posterior,  387 

at  wrist,  387 

in  forearm,  293 

in  hand,  310 

recurrent,  294 

volar,  294 
radialis  indicis,  310 
ranine  of  lingual,  94 
recurrent,  arch,  deep  palmar,  310 

interosseous,  386 

radial,  294 

tibial,  anterior  and  posterior,  594 

ulnar,  anterior  and  posterior,  296 
renal,  516 
sacra  media,  518 
sacral,  lateral,  548 

middle,  518 
scapular,  posterior,  112,  113,  370 

dorsal,  278,  371 
sciatic,  547,  613 
septal,  148,  149 
sigmoid,  512 
spermatic,  518. 
sphenopalatine,  148 
splenic,  510 

sternal  (internal  mammary),  321 
sternomastoid,  of  occipital,  96 

of  superior  thyroid,  93 
stylomastoid,  96 


Artery  or  arteries : — 
subclavian,  107 

left ,  340 
sublingual,  of  lingual,  94 
submaxillary  of  facial,  95 
submental  of  facial,  95 
subscapular,  27S,  371 
superficial  volar,  294 
suprahyoid,  94 
supra-orbital,  18,  26,  53 
suprarenal,  516 
suprascapular,  112,  371 
sural,  inferior  and  superior,  624 
system  of  brain,  cortical,  163 

ganglionic,  162 
tarsal,  external  and  internal,  593 
temporal,  26,  62 

anterior,  26 

deep,  121 

middle,  62 

posterior,  26 
thoracic,  278 

of  acromiothoracic,  272 

alar,  278 

aorta,  338 
branches  of,  345 

long,  278 

superior,  276 

thyroid  axis,  iii 

inferior,  112 

superior,  93 

thyroidea  ima,  115 

tibial,  anterior,  593 

branches,  594 

posterior,  631 
branches,  632 
tibial  recurrent,  anterior  and  posterior, 

594 
tonsillar,  95 
tracheal,  112 
transverse,  aorta,  336 

of  basilar,  164 

cervical,  112 

of  external  circumflex,  579 

facial,  62 

perineal,  412 
tympanic,  120 
ulnar,  in  forearm,  295 

in  hand,  304 

carpal,  anterior  and  posterior,  297,  388 

recurrent,  anterior  and  posterior,  296 
uterine,  547 
vaginal,  547 
vasa  brevia,  510 

intestini  tenuis,  513 
vas  deferens,  547 
vertebral,  no,  158 

vesical,  inferior,  middle,  superior,  546 
vidian,  122 
volar,  superficial,  294 
Articular  branches  of  circumflex,  poste- 
rior, 372 

of  circumflex,  internal,  580 

of  interosseous  recurrent,  386 

of  plantar,  external,  643 

of  popliteal,  624 

of  profunda,  superior  (brachial),  287, 
372 

of  sciatic,  613 

of  suprascapular,  371 


IXDEX. 


653 


Articular  branches  of  temporal,  62 
nerves  of  auriculotemporal,  28 
of  circumflex,  372 
of  crural,  anterior,  56S 
of  interosseous,  posterior,  386 
of  median,  288,  3:7 
of  obturator,  536,  583 
of  popliteal,  external,  618 

internal,  619 
of  tibial,  anterior,  598 

posterior,  631 
of  ulnar,  316 
Arjtenoideus,  146 
Arjteno-epiglottic  folds,  143 
Aryteiio-epiglottidis,  146 
Ascending  aorta,  334 
cer\-icai  artery,  iii 
colon,  476,  501 
convolution,  frontal,  22,  185 

parietal,  24,  ibo 
or  orbital  branches  of  Meckel's  gang- 
lion, 151 
palatine  artery,  95 
pharyngeal  artery,  96 
Astragalus,  head,  554 
Auditory  artery,  164 
meatus,  externus    iS 
nerve  (eighth  cranial),  204 
Auricle,  right,  354 

left.  355 
Auricular  appendix,  354,  355 
arter>",  deep,  120 
anterior,  62 
posterior.  96 
muscles,  25 
nerv-e,  gjreat,  75,  90 
Auricularis  magnus  nerve,  75,  90 
Auriculotemooral  nerve,  26,  100 
Auriculoventricular  openings,  354,  355 
valves,  355,  356 
grooves,  330 
Axilla,  boundaries   of,  257,  268,  270,  275, 

648 
Axillary  artery,  275,  276 
fascia,  268 
lymphatics,  274 
space,  648 
vein,  275 
Axis,  thyroid,  iii 

cceliac,  509 
Azygos  artery,  624 
vein,  left,  superior,  350 
major  and  minor,  348 
uvula,  144 


Back,  dissection  of,  372 

fascia  of,  362,  373 

landmarks  of,  12S,  255,  599 

muscles  of,  373 

nerves  of,  376 
Band,  iliotibial,  55S 

vocal.  145 
Bartholin,  glands  of,  428 
Basal,  ganglia  of  brain,  226,  230,  234,  236 

gray  commissure,  238 
Base  of  brain,  192 

of  bladder.  420,  537 

of  heart,  260,  330 

of  lungs,  263  358 


Base  of  skull,  interior,  38 
Basilar  artery,  158,  164 
Basilic  vein,  283 
median,  283 
Bell,  nerves  of,  external  respiratory  (long 
thoracic),  280,  315 
internal    respiratory    (phrenic),    100, 

325 
superior    respiratory    (spinal    acces- 
sory), 76,  91,  206 
Bend  of  elbow,  292 
Biceps,  285 

flexor  cruris,  608  ' 

Bicipital  artery,  279 
groove,  256 
of  humerus,  256 
Bicuspid  valve,  356 
Bile  duct,  common,  491,  492 

cystic,  491 
Biventer  cervicis,  132 
Bladder,  gall,  491 
urinary,  537 
dissection  of  interior,  548 
interior  of,  548 

ligaments  of,  lymphatics  of,  relations 
of,  vessels  and  nerves  of,  537 
peritoneal  covering  of,  537 
relations  of,  538 
Retzius'  space,  478,  537 
trigone,  external  and  internal,  420, 
540,  550 
ligaments,  false,  477,  537 
true,  401,  538 
Blood  supply  of  brain,  158 
Bodies,  suprarenal,  524 
Body  of  caudate  nucleus,  228 
of  corpus  callosum,  208 
of  fornix.  216 
geniculate,  external,  226,  230 

internal,  224 
of  lateral  ventricle,  210 
of  Luy's,  240 
olivary,  24S 
of  penis.  440 
perineal,  431 
of  pubes,  554 
of  uterus,  543 
Brachia,  or  peduncles,  corpora  quadri- 
gemina,  224 
corpus  callosum,  197,  210 
Brachial  artery,  286,  287 
plexus,  312 
veins,  2S6 
Brachialis  anticus,  285 
Brachioradialis,  292 
Brain,  i65 
base  of,  192 
blood  supply  of,  15S 
development  of,  168 
fissures  of.  176,  iSo 
ganglia  of.  226,  230,  234,  236 
hardening  of,  36 
hemispheres  of,  178 
membranes  of,  152 
relations  to  cranium,  18 
removal  of,  32,  36 
topography  of,  18 
weight  of,  648. 
Breast,  female,  266 
Bregma,  17 


654 


INDEX. 


Broad  ligament  of  liver,  486 

of  uterus,  478,  543 
Bronchi,  357 
Bronchial  arteries,  345 

veins,  359 
Bronchus,  left  and  right,  358 
Buccal  artery  (facial),  64;  (internal  max- 
illary), 121 

nerve  (facial),  61 ;  (fifth),  117 
Buccinator,  67 
Bulb,  artery  of,  412 

olfactory,  199 

of  penis,  415 

of  posterior  horn  of  lateral  ventricle,  212 

of  vagina,  427 
Bulbi  vestibuli,  427 

Bulbocavernosus  (accelerator  urinae),  410 
Bundle  of  Vic  d'Azyr,  238 
Burns'  space,  139 
Bursa  in  hand,  311 

prepatellar,  558 

subgluteal  (gluteus  maximus),  605 
Buttocks,  landmarks  of,  599 


C^CUM,  476,  500 

Calamus  scriptorius,  252 
Calcanean  artery,  external,  633 
internal,  643 
nerves,  631 
Calcar  (hippocampus  minor),  190,  212 
Calcarine  fissure  or  sulcus,  190,  194 
Callosal  sulcus,  igi,  192 
Callosomarginal  fissure  or  sulcus,  ,190 
Canal,  Alcock's,  399,  411 
alimentary,  development  of,  462 
central,  of  spinal  cord,  394 
femoral,  569 
of  Hunter,  572,  575 
inguinal,  448 
of  Nuck,  544 
"  Canals,"  anatomical,  446,  599 
Capsule,  external,  228,  234 
internal,  234 
of  Tenon,  49 
Cardiac  arteries,  left,  353 
right,  352 
nerves,  104,  354 
cervical,  104 
inferior,  107 
middle,  107 
superior,  106 
orifice  of  stomach,  494 
plexus,  deep  and  superficial,  354 
veins,  353 
Carotid  artery,  common,  loi 
left,  340 
external,  92 
internal,  98,  158 
plexus,  38,  106 

triangle,  inferior  and  superior,  83 
Carpal  artery,  radial  anterior,  294 
posterior,  3S7 
ulnar  anterior,  297 
posterior,  297,  388 
"  Carrying  angle  "  or  function,  258 
Carunculse  myrtiformes,  424 
Cauda  equina,  395 

Caudate  body,  head,  tail  of  same,  228 
lobe  of  liver,  490 


Caudate  nucleus,  226 
Cava  inferior,  354,  520 

superior,  327 
Cavernous  plexus,  106 

sinus,  43 
Cavities  of  heart,  354 
Cavity  of  great  omentum,  470 
Central  artery  of  retina,  53 
canal  of  spinal  cord,  394 
lobe  of  the  cerebrum  (island  of  Reil),  187 
Cephalic  vein,  256,  269,  283 

median,  283 
Center  of  hearing,  204 
of  sight,  200 
of  smell,  200 
Centrum  ovale  majus  and  minor,  207 
Cerebellar  arteries,  inferior  and  superior 
164 
peduncles,  244 
Cerebellum,  242 
development  of,  171,  175 
lobes  of,  242 

peduncles,  inferior  and  superior,  244 
middle,  195,  244 
Cerebral  arteries,  anterior,  158 

middle   (artery  of   cerebral    hemor- 
rhage), 160,  163 
posterior,  160,  164 
blood  supply,  158 
crura,  196 
development,  175 
flexures,  174 
hemispheres,  178 

relations  to  exterior  of  cranium,  18 
hemorrhages,  173 
veins,  165,  220 
deep,  220 
superficial,  165 
ventricles,  lateral,  211 
fifth,  216 
fourth,  248 
third,  222 
vesicles,  169 
Cerebrum,  178 
development  of,  170,  171 
fissures  of,  180 
inner  surface  of,  188 
under  surface  of,  192 
Cerebrospinal  fluid,  155,  156 

function  of,  156 
Cervical  abscess,  141 
artery,  ascending,  iii 
deep,  113,  135 
princeps  cervicis,  130 
superficial,  112,  130 
transverse,  112 
enlargement  of  spinal  cord,  394 
fascia,  deep,  136 
first  layer,  138 
fourth  layer,  140 
second  layer,  138 
third  layer,  139 
ganglion,  inferior,  107 
middle,  106 
superior,  106 
nerve  to  trapezius,  89,  91 
nerves,  89 
plexus,  89 

superficial  nerve,  75,  89,  90 
sympathetic  cord  and  ganglia,  106 


INDEX. 


655 


Cervical  vein,  deep,  iii,  136 

transverse,  74,  79 
Cervicalis  asceiideiis,  135,  376 
Cervicofacial  nerve,  61 
Cervix,  circular  artery  of,  547 

of  uterus,  543 
Chiasm  or  commissure,  optic,  197,  200 
Chorda  tympatii,  118,  203 
Chorda;  tendineae,  356 

Willisii,  34,  35 
Choroid  artery,  anterior  and  posterior, 
163 

plexuses,  development,  177,  178,  218 

vein,  222 
Choroideus  sulcus,  230 
Ciliary  arteries,  53 

nerves,  s6 
Circle  of  Willis,  15S,  162 

function  of,  161 
Circular  sinus,  44 
Circumflex  artery,  anterior,  278 
posterior,  279,  372 

femoral,  external,  579 
internal,  5S0 

iliac,  deep,  520 
superficial,  346,  557,  572 

nerve,  318,  319,  365,  372 
Circunivallate  papillae,  143 
Claustrum,  234 
Clava,  254 
Clavicle,  255 
Clavicular  artery,  272 

nerves,  76,  89.  91,  266 
Claviculo-acromial  joint,  256 
Clavipectoral  fascia,  272 
Clitoris,  423,  427 

dorsal  artery  of,  426 

glans  of,  428 

nerves  of,  428 

suspensory  ligament  of,  406,  428 
Coccygeal  artery,  613 
Coccygeus,  418 
Coeliac  axis  and  branches,  509 
Colica  dextra,  media,  sinistra,  512 
Collateral  fissure  or  sulcus,  190,  194 

digital  arteries  of  foot,  396,  643 
of  hand,  305,  388 

eminence,  190,  212 

fissure,  190,  194 
CoUes'  fascia,  404 

fracture,  258 
Colliculus  seminalis,  550 
Colon,  ascending,  476,  501 

blood  supply  of,  511,  512 

descending,  477,  501,  502 

omega  loop  of,  or  sigmoid  flexure,  477, 
502 

transverse,  476,  501 
Coluninas  carneae.  356 

rugarum  of  vagina,  431 
Comes  nervi  ischiadici,  613 

phrenici,  32S 
Commissure  basal  (gray),  238 

(cerebral),  anterior,  236 
development  of,  170,  174 

middle,  posterior,  232 

optic  (nerve),  197,  200 
Common  bile  duct,  491,  492 

carotid  artery,  loi 
left,  340 


Common  iliac  arteries,  518 
Communicans  hypoglossi,  88,  89 
peronei  nerve  (fibular),  616,  619 
phrenici,  314 
tibialis  nerve,  619 
Communicating    arteries,    anterior    and 
posterior,  160 
of  foot,  596 
of  ulnar,  304 
Comparative  measurements  of  male  and 

female  pelvis,  422 
Complexus  (and  biventer  cervicis),  132 
Compressor   of  dorsal   veins   of  penis, 
410 
urethrse,  416 
vagina,  428 
Condyles  of  femur,  554 

of  humerus,  257 
Confluence  of  sinuses  (torcularHerophili), 

35,  42 
Conjoined  tendon,  447 
Constrictors  of  pharynx,  inferior,  middle, 

and  superior,  123 
Constrictor  vaginae,  428 
Convolution  or  convolutions  : — 
angular,  187 
dentate,  192 

fornicate  (gyrus  fornicatus),  192 
frontal  lobe,  indicated   on  exterior   of 
cranium,  22 
anterior,  internal,  posterior,  194 
ascending,    inferior,    middle,    and 
superior,  1S5 
hippocampal  (gyrus  hippocampi),  192 
Ungulate,  192,  194 
marginal,  191 

occipital  lobe  indicated  on  exterior  of 
cranium,  24 
inferior,  194 

middle  and  superior,  188 
occipitotemporal,  inferior,  194 

superior,  192,  194 
operculum,  186 
orbital  (frontal),  anterior,  internal,  and 

external,  or  posterior,  194 
paracentral,  186,  191 

parietal  lobe  indicated  on  exterior  of 
cranium,  22 
ascending,   inferior    and   superior, 
186 
supramarginal,  1S6 

temporal  lobe  indicated  on  exterior  of 
cranium,  24 
inferior,  194 

inferior,  middle,  and  superior,  187 
uncinate,  191,  192,  194 
Coracobrachialis,  284 
Coracoid  process,  256 
Cord  (nerve),  lumbosacral,  529,  551 
spermatic,  coverings  for,  442 
spinal,  392 

sympathetic,  cervical,  106 
lumbar,  526 
sacral,  553 
thoracic,  345 
Cords,  vocal,  true,  and  false,  145 
Cornua  of  lateral  ventricle,  211 
Corona  glandis  of  penis,  415,  440 
of  clitoris,  42S 
radiata,  234 


656 


INDEX. 


Coronary  artery,  inferior,  64 
left,  353 
right,  352 
superior,  65 
ligament  of  liver,  473,  488 
sinus,  353 

opening  of,  354 
vein,  353 
Corpora  albicantia,  seu  mammillana,  197 
development  of,  175 
cavernosa,  416 
quadrigemina,  224 
brachia  of,  224 
development  of,  171,  175 
striata,  226 
Corpus  Arantii,  355 
callosum,  207 
body,  208 

development,  170,  173 
forceps  major,  212,  and  minor,  208 
genu,  207 

peduncles  of,  197,  210 
raphe,  210 
rostrum,  196,  208 
splenium,  207 
taeniae  tectae  and  striae  longitudinales, 

210 
tapetum,  20S 
dentatum,  246 
fimbriatum,  218 
geniculatum,  externum,  226,  230 

internum,  224 
spongiosum,  414 
striatum,  226 

development,  170,  173,  232 
vein  of,  220 
Corrugator  supercilii,  30 
Cortical  arterial  system  of  brain,  163 
hemispheres,  178 

veins  of  brain,  superior   and   inferior, 
165 
Costocolic  ligament,  471,  477 
Costocoracoid  ligament,  270 

membrane,  139,  270 
Cotunnius,  nerve  of,  152 
Counting  the  ribs,  257 
Course  of  extravasated  urine,  404, 438, 440 
Coverings  for  cord  and  testicle,  442 

how  acquired,  457 
Cowper's  glands,  417 
Cranial  nerves,  198 
eighth,  204 
eleventh,  76,  91,  206 
fifth,  46,  201 
first,  198 
fourth,  50,  201 
ninth,  98,  204 
second,  57,  200 
seventh,  61,  203 
sixth,  57,  201 
tenth,  103,  206 
third,  57,  200 
twelfth,  88,  205 
sinuses,  34 
Craniocerebral  topography,  17 
Cremaster,  448 
fascia,  448 

formation  of  muscle  and  fascia,  460 
Crest  of  ilium,  434,  557,  599 
of  occipital  bone,  external,  18 


Crest  of  tibia  (spine)  (shin),  554 
Cribriform  fascia,  556 
Cricoarytenoid,  146 

lateralis,  147 
Cricothyroid,  145 
artery,  93 
membrane,  146 
Crista  galli,  34 
Crucial  anastomosis,  580,  614 

sulcus,  224 
Crura  cerebri,  195,  238 
development  of,  171,  175 
of  diaphragm,  351 
Crural  arch,  456 
nerve,  anterior,  532,  557,  568 
septum,  526 
Crureus,  575 
Crus,  artery  of,  413 
clitoridis,  426 
penis,  416 
Crusta,  240 

Cruveilheir,  plexus  of,  112 
Cuboid  bone,  556 
Cuneate  lobe,  191,  242 
Curvature  of  stomach  greater  and  lesser,. 

494 
Cutaneous  nerve,  dorsal,  298 

external  (of  thigh),  532,  557,  561,  602 
(musculospiral),  378 
of  popliteal,  5S8 
intercostal,  anterior,  350 
internal  arm,  288,  316,  319,  378 

(thigh),  557,  562 
lateral,  350 
inferior,  superior   (musculospiral),, 
318,  365 
lesser,  internal,  316,  319,  365 
middle,  557,  562 
palmar,  298 
nerves  of  abdomen,  436,  350 
of  arm,  anterior,  283 
posterior,  365,  378 
of  back,  360 
of  dorsum  of  foot,  588,  589 

sole  of  foot,  638,  642 
of  face,  45,  61 
of  forearm,  anterior,  283 

posterior,  378 
of  gluteal  region,  602 
of  hand,  palm,  298 

dorsum,  378 
of  neck,  anterior,  75,  76 

posterior,  129 
of  shoulder,  anterior,  264 

posterior,  365 
of  thigh,  anterior,  557 

posterior,  602 
of  thorax,  anterior,  36,  264 
posterior,  350 
Cystic  artery,  510 
duct,  491 
vein,  514 


Dartos,  labium  majus,  406 

penis,  406,  415 

scrotum,  406 
Decussation    of    anterior    pyramids   of 

medulla,  248 
Deferential  artery,  547 


INDEX. 


657 


Deformity,  "gun-stock,"  25S 
Deltoid.  563 

tubercle,  256 
Dental  arteries,  121,  122 

nerves,  anterior,  middle,  posterior,  150 

plexus,  superior,  150 
Dentate  convolution,  192 

fissure,  190,  194 

ligament,  392 

nucleus,  246 
Depressor  anguli  oris,  62 

labii  inferioris,  63 
Descendens  hypoglossi,  88,  90 
Descending  aorta,  338 

colon,  477,  501,  503 
Descent  of  testicle,  457 
Development    of    abdominal     (inguinal) 
rings  and  coverings  for  the 
cord  and  testicle,  457 

of  alimentary  canal,  462 

of  aqueduct  of  Sylvius,  171,  175 

of  auditory  nerve,  171 

of  brain,  16S 

of  cerebellum,  171,  175. 

of  cerebrum,  170,  171 

of  choroid  plexuses,  177,  178 

of  commissure,  anterior,  170,  174 

of  corpora  albicantia,  175 

of  corpora  quadrigemina,  171,  175 

of  corpus  callosum,  170,  173 

of  corpus  striatum,  170,  173,  232 

of  crura  cerebri,  171,  175 

of  fissures  of  brain,  176 
of  Rolando,  176,  177 
of  Sylvius.  176 
transverse  (Eichat),  176 

of  foramina  of  Monro,  171 

of  fornix.  170,  173 

of  infundibulum,  171,  175 

of  internal  capsule,  232 

of  lamina  cinerea.  175 
terminalis,  170,  173 

of  liver,  467 

of  medulla,  171,  175 

of  olfactory  lobe,  170,  172 

of  omentum,  greater,  468 

of  optic  thalamus,  171,  173,  232 
nerve,  171 

of  pancreas,  467 

of  peritoneum,  462 

of  pineal  gland,  171 

of  pituitary  body,  171,  175 

of  pons,  171,  175 

of  septum  lucidum,  170,  173 

of  spleen,  467 

of  tuber  cinereum,  175 

of  valve  of  Vieussens,  171 

of  velum  interpositum,  177 

of  ventricles  of  brain,  fifth,    173 
fourth,  171,  176 
lateral,  170 
third,  171 

viscera    (abdominal)    and  peritoneum, 
summary  of,  4S4 
Diaphragm,  351 

openings  in,  351 
Digastric,  78 

Digital  arteries  collateral  of  hand,  305, 
388 
of  foot,  596,  643 

42 


Digital  arteries  of  hand.  304,  388 

of  foot,  643 
nerves  collateral  of  hand,  fingers,  305 
of  toes,  640 

of  fingers,  305 

of  toes,  638 
Dissection,  abdomen  exterior,  435 

interior,  473 
arm  and  forearm,  anterior,  264,  282' 

posterior,  360,  369 
axilla,  274 
back,  360,  372 
bladder  and  urethra,  interior,  548 

exterior,  536 
brain,  165,  207 
corpus  callosum,  207 
face,  deep,  115 

superficial,  58 
fascia  lata,  558,  602 
foot,  dorsum,  5S8 

sole,  634 
forearm,  282,  290,  294 

posterior,  376 
fossa,  ischiorectal,  407 
gluteal  region,  599 
hand,  anterior,  300 

posterior,  376 
head,  24 

posterior,  128 
heart.  354 
larynx,  145 
leg  anterior,  584 

posterior,  616 
nasal  fossae,  148 
neck,  anterior,  69 

posterior,  12S 
omentum,  gastrocolic,  468,  470,  476,483, 
494 

gastrohepatic,  473,  492,  494 

gastrosplenic,  506 
orbit,  48 

palm  of  hand,  300 
pelvic  viscera,  536 
penis,  435,  440 
perineum,  female,  424 

male,  404 
peritoneum,  473 
pharynx,  141 
pia,  156,  165 
removal  of  arachnoid,  156 

of  brain,  36 

of  deep  fascia  of  leg,  588,  618 

of  dura,  34 

of  fascia  lata,  562,  602 

of  heart  and  lungs  from  thorax,  343 

of  palmar  fascia,  302 

of  pia,  165 

of  plantar  fascia,  636 
shoulder,  anterior,  272 

posterior,  360 
skull,  interior  of  base,  44 
spinal  cord,  3S9 
testicle,  443 
thigh,  anterior,  556 

posterior,  599 
thorax  and  shoulder,  anterior,  264 

interior  of,  319 

posterior,  360 
ventricles,  lateral  (brain),  214 
third,  222 


658 


INDEX. 


Dissection,  ventricles  of  heart,  355 
wrist  and  hiand,  anterior,  300 
posterior,  376 
Diverticulum,  Meckel's,  471,  499 
Dorsal  artery  of  clitoris,  426 
of  penis,  superficial,  436,  573 

deep,  412,  413 
of  tongue,  94 
digital  arteries  of  hand,  388 
of  toes,  596 
nerves  of  hand,  305 
of  foot,  638 
enlargement  of  spinal  cord,  394 
nerve,  last,  529,  557,  602 
of  clitoris,  414,  426 
of  penis,  414 
nerves  of,  intercostal,  376 
veins  of  hand,  378 
of  foot,  586 
of  penis,  440,  442 
Dorsalis  hallucis,  artery,  596 
indicis  artery,  388 
lingual  artery,  94 
pedis  artery,  595 
poUicis  artery,  388 
scapulae  artery,  278,  371 
Douglas,  fold  of,  450 
pouch  of,  or  cul-de-sac,  431,  477,  483,  543 
semilunar  fold  of,  450 
Duct  or  ducts  : — 

Bartholin  glands,  424 
bile,  common,  491,492 
cystic,  491 
ejaculatory,  542,  550 
hepatic,  491 
lymphatic  right,  107 
nasal,  opening  of,  148 
of  pancreas  (Wirsung),  508 
of  parotid  gland  (Stenson's),  66 
of  prostatic  glands,  550 
of  Rivinus  (sublingual  gland),  120 
of  Stenson  (parotid  gland),  66 
thoracic,  344 
vitello-intestinal,  471 
Wharton's,  86 
of  Wirsung,  508 
Ductus  arteriosus,  332 
venosus,  490 
fissure  of,  490 
Duodenojejunal  fossa,  483,  498 

formation  of,  465 
Duodenum,  496 
impression  on  liver,  490 
ligament  of  (Treitz),  498 
Dura  of  the  brain,  32 
processes  of,  34 
of  spinal  cord,  390 


Eighth  cranial  nerve,  204 
Ejaculatory  duct,  542 

orifices  of,  550 
Elbow,  arterial  anastomosis  about,  387 

landmarks,  257 

space  anterior,  292 
Eleventh  cranial  nerve,  76,  91,  206 
Eminence,  parietal,  18 

tubal,  of  Eustachian  tube,  142 
Eminentia  collateralis,  212 
formation  of,  190 


Enlargement    of  spinal    cord,    cervical, 

dorsal,  lumbar,  394 
Ensiform  appendix,  255,  432 
Epididymis,  443 

Epigastric  artery,  deep,  454,  456 
superficial,  436,  557,  572 
superior,  321,  454 
vein,  deep,  520 
superficial,  436,  557 
Epiglottis,  143 
Epiploic  arteries,  511 
Erector  clitoridis  427 
penis,  408 
spinas,  374 
Ethmoidal  artery,  anterior  and  branches, 
54,  149 
posterior,  53,  149 
Eustachian  tube,  141,  145 

valve,  355 
Extensor  brevis  digitorum,  592 
pollicis,  384 
carpi  radialis  brevior  and  longior,  380 

ulnaris,  382 
communis  digitorum,  380 
indicis,  385 
longus  digitorum,  589 

pollicis,  384 
minimi  digiti,  381 
muscles  of  spine,  373 
ossis  metacarpi  pollicis,  382 
primi  internodii  pollicis,  384 
proprius  hallucis,  596 
secundi  internodii  pollicis,  384 
External  cutaneous  nerve  (arm),  283,  378 
thigh,  532,  557,  561,  602 
meatus,  urinary,  male,  415,  551 
female,  424 
of  ear,  18 
trigone  of  bladder,  420,  540 
Extremity,  lower,  landmarks  of  anterior, 

554 
landmarks  of  posterior,  599 


Face,  dissection  of,  deep,  115 
superficial,  58 
landmarks  of  region  of,  24 
Facial  artery,  in  face,  64 
in  neck,  94 
transverse,  62 
nerve,  61,  203 
cervicofacial  division,  61 
temporofacial  division,  61 
vein,  62 
in  neck,  74 
Falciform  ligament  or  process  of  fascia 
lata,  561 
of  liver,  486 
or  limbic  lobe  of  cerebrum,  192 
Fallopian  tube,  543,  544 
False  ligaments  of  bladder,  477,  537 

vocal  cords,  145 
Falx  cerebelli,  40 

cerebri,  34 
Fascia,  anal  or  ischiorectal,  402 
abdominal,  superficial,  436 

deep  (Scarpa's),  438 
axillary,  268 

arm  and  forearm,  deep,  283 
superficial,  264,  282 


INDEX. 


659 


Fascia,  back,  deep,  362 

superficial,  360 
cervical,  deep,  136 
first  layer,  13S 

fourth  (prevertebral)  layer,  140 
second  layer,  138 
third  layer,  139 
clavipectoral,  272 
Colles'  (perineal),  404 
costocoracoid,  270 
cremasteric,  448 

formation  of,  460 
cribriform,  556 
foot,  superficial  of  sole,  634 

dorsum,  584 
forearm,  2S2,  2S3 
gluteal  region,  superficial,  600 
hand,  2S2,  360 
iliac,  of  fascia  lata,  560 
iliopsoas,  525 
infundibuliform,  456,  460 
intercolumnar,  444 
ischiorectal,  402 
lata,  dissection  of,  558,  602 

iliac  portion,  pubic  portion,  560 

anterior  portion,  intermuscular  septa, 
iliotibial  band,  558 

internal  process,  saphenous  opening, 
560 

falciform  process,  561 

posterior  portion,  600 
removal  of,  562,  602 
leg,  deep,  5S4 

superficial,  584 
lumbar,  451 
masseteric,  59,  138 
neck, 360 
obturator,  398 
orbital,  49 
palmar,  301 
palpebral,  49 
parotid,  59,  138 
pectoral,  268 
pelvic,  398,  et  seq. 
perineal,  superficial  or  Colles',  404 

deep  or  triangular  ligaments  of,402,403 
pharyngeal,  124 
plantar,  634 

removal  of,  636 
prevertebral,  140 
pubic,  of  fascia  lata,  560 
pyriformis,  399 
rectovesical,  399,  538 
Scarpa's,  438 
shoulder,  264,  268,  360 
spermatic,  external,  444 

internal  or  infundibuliform,  456,  460 
temporal,  30 
thigh,  deep  (fascia  lata),  560,  600 

superficial,  556,  600 
thorax  anterior,  264 

posterior  (thorax  and  back),  360 
transversalis,  454 
triangular,  446 

(ligament),  402,  403 
vertebral,  373 
Fascial  sheath  of  penis,  415 
Fasciculus  teres,  252 

Fauces,  anterior  and  posterior  arches  of, 
142 


Fauces,  isthmus  of,  142 

pillars  of,  142 
Female  genitals,  external,  422 
mamma,  266 

pelvis,  measurements  of,  422 
perineum,  422 
urethra,  431 
Femoral  artery,  570 
course  of,  570 

deep  (profunda  femoris),  579 
muscular  branches  of,  573 
canal,  569 
hernia,  526,  569 
lymphatics,  557 

opening    (under    Poupart's    ligament), 
525 
(in  adductor  magnus),  578 
ring,  525 

vein  and  tributaries,  574 
veins,  cutaneous,  external  and  internal, 
557 
deep   (profunda  femoris),  and  tribu- 
taries, 574 
Femur,  condyles  of,  554 
nutrient  arterv    of,   third    perforating, 
580 
Fibres,  arciform,  external,  248,  254 

of  Gerdy,  302 
Fibula,  head  of,  554 

nutrient  artery  of,  633 
Fifth  cranial  nerve  trunks  of,  46,  201 
ventricle  of  brain,  216 

development  of,  173 
Filum  terminale,  390 
Fimbria,  218 
Fimbriated  extremity  of  Fallopian  tube, 

544 
First  cervical  nerve  (suboccipital),  136 

cranial  nerve  (olfactory),  198 
Fissure,  of  brain,  176,  180 
calcarine,  190,  194 
callosal,  191,  192 
callosomarginal,  190 
of  cerebrum,  iSo 

development  of,  176 
collateral,  190,  194 
dentate  or  liippocampal,  190,  194 
ductus  venosus,  490 
for  gall  bladder,  490 
frontal,  inferior,  superior,  and  precen- 

tral,  22,  185 
great  longitudinal,  180,  194,  196 

development,  176 
hippocampal  or  dentate,  190,  194 
intraparietal,  22,  186 
of  liver,  ductus  venosus,  490 
longitudinal,  488 
transverse,  488 
umbilical,  490 
vena  cava  inferior,  490 
longitudinal  of  liver,  4S8 
of  lungs,  outlining  on  chest,  263,  359 
of  medulla  anterior,  248 

posterior,  232 
occipital,   inferior,  middle,  and  supe- 
rior, 24,  188 
olfactory,  194 
orbital,  192 

parieto-occipital,  22,  184,  190,  194 
of  Rolando,  21,  182 


660 


INDEX. 


Fissure    of    Rolando,    development    of, 

177 
of  spinal  cord,  anterior  and  posterior, 

394 
sphenoidal,  46 
of  Sylvius,  21,  180,  194,  197 

development  of,  176 
temporal,  middle,  superior,  24,  187 

inferior,  194 
transverse  (Bichat),  180 
development  of,  176 
of  liver,  488 
umbilical  of  liver,  490 
vena  cava  of  liver,  490 
Flexor  accessorius,  640 
brevis  digitorum,  636 
hallucis,  644 
minimi  digiti,  307 

(in  foot),  646 
poUicis  (inner  head),  308 
outer  head,  306 
carpi  radialis,  291 

ulnaris,  291 
longus  digitorum,  627 
hallucis,  627 
poUicis,  29S 
profundus  digitorum,  300 
sublimis  digitorum,  294 
tendons  of  profundus   and  sublimis  in 
hand,  311 
Flexure,  hepatic,  476,  501 
sigmoid,  477,  501,  502 
splenic,  477,  501,  502 
Flexures  of  cerebral  vesicles,  174 
Flocculus,  242 

Floor  of  anterior  elbow  space,  292 
of  lateral  ventricles,  212 
of  popliteal  space,  620 
of  Scarpa's  triangle,  569 
of  third  ventricles,  198 
of  ventricles  of  brain,  fourth,  252 
lateral,  212 
third,  198 
Fluid,  cei'ebrospinal,  155,  156 
Fold  aryteno-epiglottic,  143 
of  Douglas,  450 
glosso-epiglottic,  143 
reduplicated,  of  corpus  callosum,  208 
Foot,    arteries    of,    dorsalis    pedis    and 
branches,  595,  596,  640,  642 
dissection  of  dorsum,  588 

sole,  634 
landmarks  of,  554 
veins  of,  586 
Foramen  caecum,  of  medulla,  248 
of  skull,  35 
of  tongue,  142 
dental  inferior,  118 
infra-orbital,  68,  150 
jugular,  40,  204 
Key  and  Retzius,  155,  250 
of  Majendie,  155,  250 
mastoid,  42 
mental,  58,  121 
of  Monro,  21S 

development  of,  171 
optic,  57,  200 
ovale,  48 

rotundum,  48,  149 
sacrosciatic,  greater  and  smaller,  615 


Foramen,  supra-orbital,  68 
suprascapular,  112 
of  Winslow,  470,  478 
Foramina  of  Monro,  218 
development  of,  171 
of  exit  for  cranial  nerves  from  skull, 

198,  et  seq. 
of  Key  and  Retzius,  155,  250 
of  Scarpa,  152 
of  Stenson,  149 
Thebesii,  354 
Forceps,  major  and  minor  of  corpus  cal- 
losum, 208,  212 
Forearm,  dissection  of,  282,  290,  294 
posterior,  376 
fascia  of  deep,  2S3 

superficial,  264,  282 
landmarks  of,  255 
subcutaneous  nerves  of,  283,  378 
veins  of,  282,  378 
Forebrain,  169,  170,  171 
Formation  of  abdominal  (inguinal)  rings 
and  coverings  for  spermatic 
cord  and  testicle,  457 
Fornicate  convolution  (gyrus  fornicatus), 

192 
Fornix,  body,  genua,  pillars,  anterior  and 
posterior,  216 
development  of,  170,  173 
Fossa  duodenojejunalis,  483,  498 
formation  of,  465 
intersigmoid,  483 
ischiorectal,  402,  407 
Mohrenheim's,  84 
nasal,  148 
navicularis,  424 
of  urethra,  551 
ovalis,  355 
peritoneal,  473,  482 

rectovesical,    rectovaginal,    uterovag- 
inal, 477,  483,  543 
of  Rosenmiiller,  142 
of  skull,  anterior,  middle,  posterior,  38- 
uterovesical,  477,  483,  543 
Fourchette,  424 
Fourth  cranial  nerve,  50,  201 

ventricle,  250 
Fovea,   inferior  and  superior  of  fourth 

ventricle,  252 
Fracture,  Colles',  258 
Frenum  of  epiglottis,  143 

veli,  244 
Frontal  artery,  26,  54 
bone,  angular  process,  external  and  in- 
ternal, 18 
convolutions,  ascending,  inferior,  mid- 
dle, superior,  185 
marginal,  191 

orbital  (anterior,  internal,  posterior), 
194 
lobe,  184 
convolutions  referred  to  exterior  of 
cranium,  22 
nerve,  49,  56 
sulcus  inferior,  22,  185 
orbital,  192 
precentral,  22,  185 
superior,  22,  185 
Fundus  of  stomach,  494 
of  uterus  (body),  543 


INDEX. 


661 


Funicular  process,  460 
Funiculus  cuneatus,  254 
gracilis,  254 


Galea  capitis,  25 

Galen,  vein  of,  common,  40,  222 

left  and  right,  222 
Gall  bladder,  491 
fissure  for,  490 

relations   immediate   and   superficial 
or  external,  491,  492 
Ganglia,  basal  (gray),  of  brain,  226,  250, 
234,  236  ' 
cervical,  interior,  107 
middle,  106 
superior,  106 
coccygeal,  553 
lumbar,  326 
sacral,  553 
semilunar,  509 
thoracic,  345 
Ganglion,  Gasserian,  46 
geniculate  (facial),  202 
inipar,  5S3 

jugular  (ninth  cranial  nerve),  204 
Meckel's,  sphenopalatine  or  nasal,  151 
ophthalmic,  lenticular,  or  ciliary,  56 
otic,  119 

petrous  (ninth),  204 

of  pneumogastric  (root  and  trunk),  103 
submaxillary,  119 
Ganglionic  arterial  system  of  brain,  162 
anterolateral  group,  162 
anteromedian  group,  162 
posterolateral  group,  162 
posteromedian  group,  163 
veins  of  brain,  220 
Gasserian  ganglion,  46 
Gastric  artery,  509 

vein,  514 
Gastrocnemius,  620 
Gastrocolic  omentum,  468,  470,  476,  483, 

494 
Gastroduodenalis  artery,  510,  511 
Gastro-epiploic  artery,  left,  510 
right,  511 
veins,  512,  514 
Gastrohepatic  omentum,  473,  492,  494 
Gastrophrenic  ligament,  473,  494 
Gastrosplenic  omentum,  506 
Gemelli,  inferior  and  superior,  606 
Geniculate  body,  external,  226,  230 
internal,  224 
ganglion  (faciall,  202 
Geniohyoglossus,  97 
Geniohyoid,  96 
Genitals,  external,  female,  422 

male,  440 
Genitocrural  nerve,  532,  557 
Genua  of  fissure  of  Rolando,  182 
Genu,  corpus  callosum,  207 
fornix,  216 

of  internal  capsule,  234 
Gerdy,  fibres  of,  302 
Ginibernat's  ligament,  445 
Glabella,  17 
Gland  or  glands  : — 
Bartholin,  428 
Cowper's,  417 


Gland  or  glands : — 

lachrymal,  50 

mammary,  266 

Pacchionian,  155 

parotid,  66 

pineal,  224 

pituitary,  171,  175,  197 

prostatic,  550 

sublingual,  119 

submaxillary,  85 

thymus,  324 

thyroid,  114 
Glans  clitoridis,  423,  428 

penis,  415,,  440 
Globus  pallidus  (lenticular  nucleus),  230 
Glosso-epiglottic  folds,  143 

pouch,  143 
Glossopharyngeal  nerve,  98,  204 
Glottis  (larynx),  145 

rima,  145 
Gluteal  artery,  548,  612 

nerve,  inferior,  552 
superior,  551,  616 

region,  dissection  of,  599 
landmarks  of,  599 

vein,  548 
Gluteus  maximus,  602 

bursa  under  the  muscle,  605 

medius,  605 

minimus,  615 
Gracilis,  566 
Great  auricular  nerve,  75,  89,  90 

deep  petrosal  nerve,  46,  151 

longitudinal   fissure   of  cerebrum,  180, 
196 
development,  176 

occipital  nerve,  129 

omentum,  468,  470,  476,  4S3,  494 
cavity  of,  470 

sacrosciatic  toranien,  615 
ligament,  614 

sciatic  nerve,  553,  610 

splanchnic  nerve,  345 

superficial  petrosal  nerve,  151,  203 

synovial  bursa  of  palm  of  hand,  311 

transverse  fissure  of  cerebrum,  180 
development,  176 

trochanter,  554 

tuberosity  of  humerus,  256 
Groin,  see  inguinal  region,  435 

landmarks  of,  432 

lymphatics  of,  436 
Groove,  anterolateral  of  medulla,  248 

auriculoventricular,  330 

bicipital,  256 

interventricular,  330 

lateral  of  crus  cerebri,  240 

oculomotor,  240 
Gubernacukim,  457 
Gun-stock  deformity,  258 
Gustatory  nerve,  118 
Gyrus,  angular,  187 

fornicatus,  192 

hippocampi,  192 

uncinate,  191,  192,  194 


Ham-strings,  599 
Hand,  dissection  of,  300 
posterior,  376 


662 


INDEX. 


Hand,  synovial  membrane  of,  311 
Hardening  of  brain,  36 
Head,  anterior,  17 

of  astragalus,  554 

of  caudate  nucleus,  228 

dissection  of,  24,  128 

of  fibula,  554 

of  humerus,  257 

landmarks  of  anterior,  17 
of  posterior,  128 

of  pancreas,  508 

posterior,  dissection  of,  128 

of  radius,  257,  258 
Heart,  330 

apex,  260 

arteries  of  (coronary  right  and  left), 
352,  353 

auricles,  354,  355 

cavities  of,  330 

dissection  of,  354 

dullness,  260 

openings  of,  354,  355,  356 

outlining  on  chest  wall,  260 

position  of,  259,  331 

relation  to  chest  wall,  260 

size  and  weight,  330 

valves  of,  355,  356 

veins  of,  353 

ventricles,  left,  356 
right,  355 
Hemispheres  of  cerebellum,  242 

of  cerebrum,  178 
Hemorrhoidal  artery,  inferior,  412 
middle,  547 
superior,  514 

nerve,  inferior,  413 

plexus,  408 

veins,  40S 
Hepatic  artery,  510 

duct,  491 

flexure  of  colon,  476,  501 

impression  on  liver,  490 

vein,  521 
Hernia,  course  of  direct  and  indirect,  in- 
guinal, 460,  461 

coverings   for  direct   and  indirect  in- 
guinal, 461 

femoral,  526,  569 

nature's  protection  against  ventral  her- 
nia, 452 

varieties  of  direct  and  indirect  inguinal, 
460,  461 
Hesselbach's  triangle,  457 
Highmore,  antrum  of,  opening  of,  148 
Hindbrain,  169,  171,  175 
Hippocampal  convolution,  192 

or  dentate  fissure,  190,  194 
Hippocampus  major,  214 
formation  of,  190 

minor,  212 
formation  of,  190 
Horns  of  lateral,  ventricle,  anterior,  mid- 
dle or  descending,  posterior, 
210 
Humeral  artery,  272,  278 
Humerus,  nutrient  artery  of,  287 
Hunter's  canal,  572,  575 
Hydrocele,  460,  461 
Hymen,  424 
Hyoglossus,  97 


Hyoid  artery  of  lingual,  94 
of  superior  thyroid,  93 
Hypogastric  artery,  obliterated,  538,  547 
Hypoglossal  (cranial)  nerve,  88,  206 

loop,  88 
Hypoglossi  ansa,  88 

communicantes,  88,  89,  90 

descendens,  88,  90 
Hypophysis,  175,  197 


Ileocolic  artery,  512 

valve,  499 
Ileum,  499 

Iliac  artery,  circumflex  deep,  519 
superficial,  557,  572 
common,  518 
external,  519 
internal,  546 
portion  of  fascia  lata,  560 
vein,  common,  520 
circumflex  deep,  520 

superficial,  557 
external,  520 
internal,  548 
Iliacus,  527 
Iliocostalis,  375 
Iliohypogastric  nerve,  440,  450,  451,  530, 

602 
Ilio-inguinal  nerve,  448,  451,  530,  557 
Iliolumbar  artery,  548 
Iliopsoas  fascia,  525 
Iliotibial  band,  558 
Impar  ganglion,  553 

Impressions  on  the  liver  for  duodenum, 
490 
for  hepatic  flexure,  490 
for  right  kidney,  490 
for  stomach,  490 
Inferior  longitudinal  sinus,  36 
maxillary  nerve,  48,  117 
petrosal  sinus,  42 
pudendal  nerve,  406,  604 
vena  cava,  575 

fissure  in  liver  for.  490 
Inframaxillary  nerve,  61,  74 
Infra-orbital  artery,  122 
canal,  150 
foramen,  68,  150 
nerve,  5i 
plexus,  61,  151 
Infraspinatus,  368 
Infratrochlear  nerve,  56 
Infundibuliform  fascia  (internal  sperma- 
tic), 456,  460 
Infundibulum,  197 
development  of,  171,  175 
frontal  sinus,  148 
opening  of  into  nasal  fossa,  148 
Inguinal  canal,  448 
hernia,  course  of,  460,  461 
coverings  for,  461 
varieties  of  460,  461 
lymphatics,  436 
rings,  external,  444 
internal,  456 
formation  of,  457 
Inion,  18 

Innominate  artery,  339 
veins,  92,  326 


INDEX. 


663 


Interbrain,  169,  171,  175 
Interclavicular  notch,  255 
Iiitercoluninar  fascia,  444 
Intercostal  arteries,  346 
anterior,  321 
aortic,  346 
artery,  superior,  346 
muscles,  external,  346 
internal,  347 
action  of,  347 
nerves,  350,  376,  451 

cutaneous  branches,  266,  282,  451 
veins,  348 
left  and  right  superior,  350 
Intereostohumeral  nerve,  266,  280,  282, 319, 

351.  365 
Internal  capsule,  234 

development  of,  232 
Interossei  of  foot,  dorsal,  592 
of  hand,  dorsal,  388 

palmar,  309 
sole  of  foot,  646 
Interosseous  artery,  anterior,  296,  386 
common,  296 
of  foot,  dorsal,  595 
of  hand,  dorsal,  3S8 

palmar,  310 
posterior,  297,  385 
recurrent,  386 
nerve,  anterior,  317 
posterior,  293,  318,  386 
Interpeduncular  space,  198 
Intersigmoid  fossa,  483 
Interventricular  (coronary)  artery,  left, 
353 
right,  352 
groove,  330 
vein,  anterior,  353 
posterior,  353 
Intestinal  blood  supply,  509,  et  seq. 
Intestine,  496 
development  of,  462 
large,  500 
appendices  epiploicse,  500 
muscular  bands  of,  500 
sacculated  formation,  500 
divisions  of, 
ascending  colon,  476,  501 
caecum,  soo 

descending  colon,  477,  501,  502 
omega  loop  or  sigmoid  flexure,  477, 

501,  502 
rectum,  504 

splenic  flexure,  501,  502 
transverse  colon,  476,  501 
vermiform  appendix,  500 
relation  to  surface  of  body,  505 
rotation  of,  464 
small,  499 
divisions  of, 

duodenum,  496 
ileum,  499 
jejunum,  499 
Intraparietal  sulcus,  22,  186 
Ischiocavernosus  (erector  penis)  408 
Ischiorectal  fascia,  402 
fossa,  402,  407 

dissection  of,  407 
region,  397 
Ischium,  tuberosity  of,  599 


Island  of  Reil,  187 
Isthmus,  of  fauces,  142 

of  gyrus  fornicatus,  192 

of  thyroid  gland,  114 

of  uterus,  543 

Jacobson's  nerve,  206 
Jejunum,  499 

Jugular  ganglion  (ninth  nerve),  204 
vein,  anterior,  74,  99 

external,  74,  99 

internal,  92 

posterior  external,  74 

Key  and  Retzius,  foramina  of,  155,  250 
Kidney,  522 

arteries  of,  524 

dissection  of,  515 

impression  of  right,  on  liver,  490 

lymphatics  of,  524 

nerves,  524 

relations  of,  522 

situation  of,  522 

size  of,  522 

veins  of,  524 
Knee  of  corpus  callosum,  207 

of  fornix,  216 

of  internal  capsule,  234 
Knee-joint,  arterial    anastomosis    about, 
624,  626 

nerves  to,  618,  6ig 
Knees  of  fissure  of  Rolando,  182 


Labbe,  vein  of,  165 

Labia  majora  and  minora,  423 

Labial  artery,  inferior,  64 

nerves  (superior  maxillary),  151 
Labium  majus,  dartos  of,  406 
Lachrymal  artery,  50,  53 

gland,  50 

nerve,  50,  56 
Lacuna  magna,  551 
Lacunae  of  urethra,  551 
Lambda,  17 
Lamina  cinerea,  196 
development  of,  175 

quadrigemina,  224 

terminalis,  170,  173 
Landmarks  of  abdomen,  432 

of  arm,  257 

of  axillary  space,  257 

of  back,  128,  255,  599 

of  cranium,  17 

of  elbow,  257 

of  face,  24 

of  foot,  554 

of  forearm,  255 

of  gluteal  region,  599 

of  hand,  255 

of  head  anterior,  17 
posterior,  128 

of  leg,  554 

of  neck,  anterior,  68 
posterior,  128 

of  perineum,  female,  422 
male,  397 

of  popliteal  space,  599 

of  shoulder,  256 


664 


INDEX. 


Landmarks  of  thigh,  anterior,  432,  554 
posterior,  599 
of  thorax,  anterior,  255,  432 

posterior,  319 
of  wrist,  258, 
Large  intestine,  500 

Laryngeal  artery  (inferior  thyroid),  112 
(superior  thyroid),  93 
nerve,  inferior  or  recurrent,  104 
left,  341 
superior,  103 
Larynx,  arteries  of,  146 
dissection  of,  145 
fossa  innominata,  146 
interior  of,  145 
nerves  of,  146 

nerve  supply  to  muscles,  147 
ventricles  of,  146 
Last  dorsal  nerve,  529,  557,  602 
Lateral  area  of  medulla,  248,  252 
columns  of  medulla,  248,  252 
cutaneous     branches     of     intercostal 

nerves,  350 
groove  in  crura  cerebri,  240 
ligaments  of  liver,  473,  488 

of  uterus,  478,  543 
nasal  artery,  65 
sacral  arteries,  548 
sinuses  of  skull,  21,  40,  92 
ventricle,  210 
body,  210 
bulb,  212 
floor  of,  212 
horns,    anterior,    middle,   posterior, 

210 
roof  of,  210 
Latissimus  dorsi,  364 
Leg,  dissection  of,  anterior,  584 
posterior,  616 
fascia  of,  deep,  584,  588 

superficial,  5.84 
landmarks  of,  554 
nerves  of,  cutaneous,  588,  616,  619 
veins  of,  cutaneous,  586,  618 
Lenticular  ganglion  (ophthalmic,  ciliarj'), 
56 
nucleus,  228 
Lenticulostriate  artery,  162 

in  cerebral  hemorrhage,  173 
Lesser  occipital  nerve,  75,  89,  90,  129 
omentum,  473,  492,  494 
sac     of    peritoneum     (sac     of    greater 

omentum),  470 
splanchnic  nerve,  345 
superficial  petrosal  nerve,  203 
Levator  anguli  oris,  60 
scapulae,  366 
ani,  417 

glandulse  thyroideas,  98 
labii  inferioris,  63 
superioris,  60 
alaequae  nasi,  60 
menti  (labii  inferioris),  63 
palati,  144 

palpebrse  superioris,  50 
Ligament  or  ligaments  : — 
annular  of  ankle,  anterior,  584 
external,  585 
internal,  586 
of  wrist,  anterior,  302 


Ligament  or  ligaments : — 
annular  of  wrist,  posterior,  378 
of  bladder,  false,  477,  537 

true,  401,  538 
broad,  of  liver,  486 

of  uterus,  478,  543 
of  clitoris,  suspensory,  406,  428 
coronary,  of  liver,  473,  488 
costocolic,  471,  477 
costocoracoid,  270 
duodenum  (Treitz),  498 
falciform  of  fascia  lata,  561 

of  liver,  486 
gastrophrenic,  473,  494 
Gerdy,  302 
Gimbernat's,  445 
lateral  of  liver,  473,  48S 

of  uterus,  478,-  543 
of  liver,  486 
musculus     suspensorius     duodeni 

(Treitz),  498 
of  ovary,  543,  544 
palm,  superficial,  transverse,  301 
penis,  suspensory,  406,  438,  440 
peritoneal,  of  bladder,  477,  537 

of  colon  (costocolic),  471,  477 

of  liver,  473,  486,  488 

of  rectum,  477 

of  spleen,  phrenosplenic,  506 

of  stomach,  gastrophrenic,  473,  494 

of  uterus,  broad,  478,  543 
phrenocolic,  471,  477 
phrenosplenic,  506 
Poupart's,  434,  445,  554 
prostate,  401 
pterygomaxillarj',  123 
puboprostatic,  402 
rectum,  401 
round  of  liver,  488 

of  uterus,  544 
sacrosciatic,  great,  614 

small,  615 
stylohyoid,  123 
stylomaxillary,  123,  138 
suspensory  of  clitoris,  406,  428 

of  duodenum,  498 

of  liver,  473,  486 

of  penis,  438,  440 
tarsal  external  and  internal,  29 
transverse  superficial  of  palm,  301 
Treitz,  498 
triangular  of  perineum,  deep,  402 

superficial,  403 
uterus,  477,  543,  544 
vaginal  ligaments  (fingers),  303 
wrist,  anterior,  302 

posterior,  378 
Zinn,  52 
Ligamentum    arcuatum    externum,   451, 

525 
internum,  525 
denticulatum,  392 
nuchse,  362 
patellae,  576 
splenis,  471,  477 

sustentaculum  hepatis,  471,  476 
Limbic  lobe,  192 

Limbs  internal  capsule,  anterior  and  pos- 
terior, 234 
Line,  nasolambdoidal,  21 


INDEX. 


665 


Line,  Nelaton's,  554,  599 

white,  of  obturator  fascia,  399,  400 
Linea  alba,  444 

semilunaris,  450 
Linese  transversa;,  435,  453 
Lingual  artery,  94 
nerve  iiS 
tonsil,  143 
triangle,  85 
Lingula  (cerebellum),  244 
Lingulate  convolution,  192,  194 
Liver,  4S6 
anterior  border  of,  491 
development  of,  467 
fissures  of,  4SS 
impressions,  490 
colic  (hepatic  tiexure), 
duodenal, 
gastric, 

renal  (right  kidney), 
ligaments  of,  486,  48S 
lobes  of,  488 
notch,  interlobular,  493 
relations,  48S 
surface,  491 
size,  4S6 
surfaces,  488 
weight,  486 
Lobes  of  cerebellum,  242 
amygdaloid,  242 
cuneate,  242 
flocculus,  242 
postero-inferior,  242 
posterosuperior,  242 
quadrate,  242 
slender,  242 
tonsillar,  242 
vermiform,  242 
of  cerebrum,  central  (insula),  187 
cuneiform,  19; 
falciform  or  limbic,  192 
frontal,  22,  184 
island  of  Reil,  187 
limbic,  192 
occipital,  24,  18S 
olfactory,  172,  ig8 
parietal,  22,  186 
temporal,  24,  187 
quadrate,  191 
of  liver,  caudate,  490 

lateral,  left  and  right,  488 
quadrate,  490 
Spigelian,  490 
of  lung,  left,  358 
right,  35S 
Locus  cseruleus,  252 

niger,  240 
Long  or  middle  subscapular  nerve,  318 
or  internal  saphenous  nerve,  534,  566,588 

vein,  557,  574,  586 
thoracic  artery,  278 
Longissimus  dorsi,  374 
Longitudinal  fissure  (great),  brain,  180, 
194,  196 
of  liver,  488 
sinus,  inferior,  36 
superior,  20,  34 
Longus  colli,  127 

Lower  extremity,  dissection  of,  anterior, 
556 


Lower  extremity,  dissection  of,  posterior, 

599 
landmarks  of,  anterior,  554 
posterior,  599 
Lower,  tubercle  of,  355 
Lumbar  arteries,  51S 

enlargement  of  spinal  cord,  394 

fascia,  451 

ganglia  of  sympathetic  cord,  526 

nerves,  376 

plexus,  529 

sympathetic  cord,  526 

veins,  521 
ascending,  34S,  521 
Lumbosacral  cord,  529,  551 
Lumbricales,  of  foot,  641 

of  hand,  307 
Lung,  apex,  base,  surfaces,  262,  358 

bordeis,  fissures,  root,  359 

outlining  on  chest,  262 
fissures  of,  263,  359 

nerves,  vessels  of,  359 

reaches  into  base  of  neck,  262,  338 
Lunated  space  in  semilunar  valves,  355 
Luy's  body  or  nucleus,  240 
Lymphatics,  of  abdomen  (inguinal),  436 

of  araclmoid,  156 

of  axilla,  274 

femoral,  557 

inguinal,  436 

mammary,  266 

ovarian,  546 

uterine,  546 

vaginal,  546 

vulvar,  546 
Lymphatic  duct,  right,  107 

thoracic,  344 
Lyre  of  the  fornix,  21S 


Majendie,  foramen  of,  155,  250 
Malar  nerve  (superior  maxillary),  150 
(facial,  temporofacial  division),  61 
Male  genitals,  440 

peruieum,  397 
Malleolar  arteries,  external  and  internal, 
594 
internal,  594,  633 
Malleoli,  external  and  internal,  554 
Malleolus,  internal,  relations  behind,  632 
Mammary  artery,  external,  279 
internal,  113,  320,  346 
gland,  266 
lymphatics,  266 
vessels  and  nerves,  266 
Manubrium,  255 
Marginal  convolution,  191 

sinuses,  42 
Marshall,  oblique  vein  of,  353 
Masseter,  67 

Masseteric  artery,  branch  of  facial,  64 
of  internal  maxillary,  121 
fascia,  59,  138 
nerve,  X17 
Mastoid  process,  18 

Maxillary  antrum  I  of  Highmore), opening 
of,  148 
artery,  internal,  120 
nerve,  inferior  division  of  fifth,  48,  117 
superior  division  of  fifth,  48,  149 


666 


INDEX. 


Maxillary  vein,  internal,  72 
"  McBurney's  point,"  501 
Measuring  for  shortening  in  lower  ex- 
tremity, 434,  554 
upper  extremity,  256 
Meatus,  auditory,  external,  18 
nasal,  inferior,  middle,  superior,  148 
urinary,  female,  external,  424 
male,  external,  415,  551 
(and  female),  internal,  548 
Meckel's  diverticulum,  471,  499 
(or  nasal  or  sphenopalatine)  ganglion, 

151 
Median  artery,  297 
nerve,  288,  298,  317 
vein,  282 
basilic,  283 
cephalic,  283 
Mediastinal  arteries,  321. 

veins,  327 
Mediastinum,  322 
anterior,  middle,  superior,  322 
posterior,  323 
testis,  443 
of  thorax,  322 
Medulla,  196,  246 
development  of,  171,  175 
fissures  of,  anterior,  248 
posterior,  252 
Medullary  laminae,  230 
velum, inferior  (tela  choroidea,  inferior), 
220,  250 
superior   (tela  choroidea,  superior), 
220 
Membrane,  costocoracoid,  270 
cricothyroid,  146 
thyrohyoid,  146 
Membranes  of  brain,  arachnoid,  154 
dura,  32 
pia,  156 
of  spinal  cord,  arachnoid,  390 
dura,  390 
pia,  392 
Meningeal  artery,  anterior,  44 
of  ascending  pharyngeal,  44 
middle,  44,  121 
posterior,  44,  96 
small,  121 
nerves  of  glossopharyngeal,  206 
of  hypoglossal,  206 
of  inferior  maxillary,  117 
of  pneumogastric,  103 
of  superior  maxillary,  150 
Meninges  of  brain  and  spinal  cord,  see 

membranes  of  same  above 
Mental  artery  (facial),  95 
(inferior  dental),  121 
foramen,  68,  121 
nerve,  68,  118 
Mesenteric  artery,  inferior,  512 
superior,  511 
vein,  inferior,  514,  515 
superior,  512,  514 
Mesentery,  463,  472,  476,  499 
development  of,  463 
of  sigmoid  flexure  or  omega  loop,  504 
of  testicle,  457 
of  vermiform  appendix,  476 
Mesocolon,  transverse,  463,  476 
Mesoduodenum,  463 


Mesogaster,  463 
Mesorchium,  457 
Mesorectum,  504 
Metacarpal  artery,  388 
Metatarsal  artery,  595 
Midbrain,  169,  171,  175 
Mitral  valve,  356 
Mohrenheim's  fossa,  84 
Monro,  foramen  of,  171,  218 
Mons  veneris,  423 
Morgagni,  sinus  of,  126 
Motor  oculi  nerve  (third  cranial),  57,  200 
Muscle : — 
abdominal  muscles, nerve  supply  for, 453 
abductor  hallucis,  637 
minimi  digiti,  306,  637 
pollicis,  306 
accelerator    urinae    (bulbocavernosus), 

410 
accessorius,  375 
adductor  brevis,  576 
hallucis,  644 
longus,  566 
magnus,  578 
pollicis  (obliquus),  308 
(trans versus),  308 
anconeus,  381 
aryteno-epiglottidis,  146 
arytenoideus,  146 
auricular,  25 
azygos  uvulae,  144 
biceps,  285 

biceps  flexor  crureus,  608 
biventer  cervicis,  132 
brachialis  anticus,  285 
brachioradialis,  292 
buccinator,  67 
bulbocavernosus    (accelerator  urinse), 

410 
cervicalis  ascendens,  135,  376 
coccygeus,  418 

complexus  (and  biventer),  132 
compressor  urethrae,  416 
vaginas,  428 

venae  dorsalis  penis,  410 
constrictor,  inferior,  middle,  superior 
(of  pharynx),  125 
vaginae,  428 
coracobrachialis,  284 
corrugator  supercilii,  30 
cremaster,  448 

formation  of,  460 
crico-arytenoid,  146 

lateralis,  147 
cricothyroid,  145 
crureus,  575 
deltoid,  363 
depressor  anguli  oris,  62 

labii  inferioris,  63 
diaphragm,  351 
digastric,  78 
erector  clitoridis,  427 
penis,  408 
spinse,  374 
extensor  brevis  digitorum,  592 
pollicis  (primi  internodii),  384 
carpi    radialis  brevior  and  longior, 
380 
ulnaris,  382 
communis  digitorum,  380 


INDEX. 


667 


Muscle,  extensor  indicis,  385 
longus  digitorum,  ^89 

pollicis  (secuiidi  internodii),  3S4 
minimi  digiti,  3S1 
muscles  of  spine,  373 
ossis  metacarpi  pollicis,  382 
primi  internodii  pollicis,  384 
proprius  hallucis,  590 
secundi  internodii  pollicis,  384 
flexor,  accessorius,  640 
brevis  digitorum,  636 
hallucis,  644 
minimi  digiti,  307,  646 
pollicis  (inner  liead),  308 
(outer  head),  306 
carpi  radialis,  291 

ulnaris,  291 
longus  digitorum,  627 
hallucis,  627 
pollicis,  298 
profundus  digitorum,  300 
sublimis  digitorum,  294 
tendons  in  palm  of  hand,  311 
foot,  lirst  layer,  636 
fourth  layer,  646 
second  layer,  640 
third  layer,  644 
gastrocneinius,  620 
gemelli,  inferior  and  superior,  606 
geniohyoglossus,  97 
geniohyoid,  96 
gluteus  maximus,  602 
medius,  605 
minimus,  615 
gracilis,  566 
hyoglossus,  97 
iliacus,  527 

iliocostals  (sacrolumbalis),  375 
infraspinatus,  368 
intercostals,  external,  346 

internal,  347 
interossei  of  foot,  dorsal,  592 
plantar,  646 
of  hand,  dorsal,  38S 
palmar,  309 
ischiocavernosus  (erector  penis),  408 
larynx,  muscles  of,  nerve  supply  for,  147 
latissimus  dorsi,  364 
levator  anguli  oris,  60 
scapulae,  366 
ani,  417 

glandulae  thyroideae,  115 
labii  inferioris,  63 
superioris,  60 
levator  labii  superioris  alaequae  nasi,  60 
proprius,  60 
menti  (labii  inferioris),  63 
palati,  144 

palpebrae  superioris,  50 
longissimus  dorsi,  374 
longus  colli,  127 
lumbricales  of  foot,  641 

of  hand,  307 
masseter,  67 
mylohyoid,  81 

obliquus  abdominis  externus,  443 
internus,  447 
capitis,  inferior  and  superior,  134 
inferior,  .sS 
superior,  50 


Muscle,  obturator  externus,  582 

internus,  606 
occipitofrontalis,  25 
omohyoid,  79 
opponens  minimi  digiti,  309 

pollicis,  309 
orbicularis  oris,  63 

palpebrarum,  28 
palatoglossus,  144 
palatopharyngeus,  143 
palmaris  brevis,  300 

longus,  291 
pectineus,  565 
pectoralis  major,  268 

minor,  274 
peroneus  brevis,  630 

longus,  630 

tertius,  590 
plantaris,  621 
platysma  myoides,  70 
popliteus,  621 
pronator  radii  quadratus,  648 

teres,  290 
psoas  magnus,  527 

parvus,  528 
pterygoideus  externus,  123 

internus,  124 
pyraniidalis,  453 

nasi,  29 
pyriformis,  605 
quadratus  femoris,  607 

lumborum,  528 

menti  (depressor  labii  inferioris),  63 
quadriceps  extensor  femoris,  576 
rectus  abdominis,  453 
sheath  of,  454 

capitis  anticus,  major  and  minor,  126 
lateralis,  126 
posticus,  major  and  minor,  134 

externus  (eye),  52 

femoris,  565 

inferior,  58 

internus,  52 

superior,  52 
rhomboideus,  major  and  minor,  366 
risorius,  59 

sacrolumbalis  (iliocostalis),  375 
salpingopharyngeus,  145 
sartorius,  562 
scalenus  anticus,  100 

medius,  100 

posticus,  loi 
semimembranosus,  609 
semitendinosus,  609 
semispinalis  colli,  135 
serratus  magnus,  279 

posticus,  inferior  and  superior,  370 
soleus,  622 

sphincter  ani  externus,  407 
internus,  422 

vaginae,  427 
spinalis  dorsi,  374 
splenius  capitis  et  colli,  131 
sternocleidomastoid,  76 
sternohyoid.  80 
sternothyroid,  80 
styloglossus,  97 
stylohyoid,  79 
stylopharyngeus,  97 
subanconeus,  369 


668 


INDEX. 


Muscle,  subclavius,  272 
subcrureus,  5S2 
subscapularis,  279 
supinator  brevis,  3S5 

longus,  292 
supraspinatus,  366 
temporal,  30 
tensor  palati,  144 

vaginae  femoris,  564 
teres,  major  and  minor,  368 
thj'ro-arytenoid,  147 
thyrohyoid,  80 
tibialis  anticus,  589 

posticus,  628 
trachelomastoid,  131,  375 
transversalis  abdominis,  451 

cervicis  (colli),  135,  374 
transversus  pedis,  646 
perinasi,  deep,  416 
superficial,  410 
trapezius,  362 
triangularis  sterni,  320 
triceps,  369 

vastus  externus  and  internus,  575 
zygomaticus,  major  and  minor,  59 
Muscles  moving  the  vocal  cords,  147 
Muscular  bands  of  the  large  intestine,  500 

fasciae  of  orbit,  49 
Musculi  papillares,  356 

pectinati,  355 
Musculocutaneous  nerve  (arm),  2S8,  315 
319.  378 
(leg),  588 
Musculophrenic  artery,  321 
Musculospiral   nerve,   290,   318,  319,  365, 

372,  378    .  . 

Musculus   suspensonus    duodeui   (Liga- 
ment of  Treitz),  49S 
Mylohyoid  artery,  121 
muscle,  81 
nerve,  81,  118 


Nares,  posterior,  141 
Nasal  artery,  54 
lateral,  65 

duct,  opening  of,  148 

fossEe,  dissection  of,  148 
openings  into,  148 

(Meckel's)  ganglion,  151 

nerves,  56,  149,  151,  152 

or  nasopalatine  artery,  122 
Nasion,  17 

Nasolambdoidal  line,  21 
Nasopalatine  artery,  148 

nerve,  148,  152 
Nates  of  corpora  quadrigemina,  224 
Neck  dissection,  anterior,  69 
posterior,  128 

landmarks  of  anterior,  68 
posterior,  128 

of  penis,  415,  440 

triangles  of,  81 

veins  of,  74 
Nelaton's  line,  554,  599 
Nerve  or  nerves:  — 

abducens  (sixth  cranial),  57,  201 

acromial,  76,  89,  91,  266,  365 

ansa  hypoglossi,  88 

anterior  crural,  532,  557,  568 


Nerve  or  nerves  : — 
of  arachnoid  membrane,  156 
articular  to  knee,  618,  619 
auditory,  204 
auricular  (facial),  61 
auricularis  niagnus,  75,  89,  90 
auriculotemporal,  26,  117 
of  back, 376 
Bell,  respiratory, 
external  (long  thoracic),  280,  315 
internal  (phrenic),  100,  325 
superior  (spinal  accessory),  76,  91,  206 
buccal  (facial),  61 

(fifth),  117 
calcanean,  631 

calcaneoplantar  cutaneous,  631 
cardiac,  104, 354 
cervical,  104 
inferior,  107 
middle,  107 
superior,  106 
carotid  plexus,  48,  106 
cavernous  plexus,  106 
cervical  cardiac,  104,  106,  107 
cord  and  ganglia,  io5 
nerves,  89 
plexus,  89 

superficial,  75,  89,  90 
cervicofacial,  division  of  facial,  61 
chorda  tympani,  118,  203 
ciliary,  56 

circumflex,  318,  319,  365.  372 
clavicular,  76,  89,  91,  266 
communicans  hypoglossi,  88,  89 
fibularis,  616,  619 
peronei,  619 
phrenici,  314 
tibialis,  616,  619 
cranial,  198 
eighth,  204 
eleventh,  76,  91,  206 
fifth,  46,  201 
first,  19S 
fourth,  50,  201 
ninth,  98,  204 
second,  57,  200 
sevenlli,  61,  203 
sixth,  57,  201 
tenth,  103,  2o5 
third,  57,  200 
twelfth,  88,  206 
crural  anterior,  532,  557,  568 
Cruveilheir,  plexus  of,  112 
cutaneous  nerves  of  abdomen,  436,  350 
of  arm,  anterior,  283 
posterior,  365,  378 
of  back, 360 
of  chest,  264,  350 
of  face,  46,  61 
of  foot,  dorsum,  588,  598 

sole,  638,  642 
of  forearm,  anterior,  283 

posterior,  378 
of  gluteal  region,  602 
of  hand,  dorsum,  378 

palm,  298 
of  head,  anterior,  25,  46,  49,  61,  75, 
129 
posterior,  129 
of  leg,  anterior,  588 


INDEX. 


669 


Nerve  or  nerves  : — 
cutaneous,  of  leg,  posterior,  6i6,  619 
of  neck,  anleiior,  75,  76 

posterior,  129 
of  perineum,  406,  413 
of  shoulder,  anterior,  264 

posterior,  365 
of  thigh,  anterior,  557 

posterior,  602 
of  thorax,  anterior,  264,  350 
posterior,  360 
dorsal  of  foot,  588,  589 

hand,  298,  378 
external  (musculocutaneous),  283 
(musculospiral),  378 
(thigh),  532,  557,  561,  602 
internal  (.arm),  288,  316,  319,  378 
lesser,  316,  319,  365 
(thigh),  557,  562 
inferior  (musculospiral),  318,  365 
middle  (thigh*),  557,  562 
palmar,  298 

superior  (musculospiral),  318,  365 
dental,     anterior,     middle,     posterior, 
superior,  150 
inferior,  117 
descendens  hyiioglossi,  88,  90 
digital  of  foot,  638 
of  hand,  305 
collateral  of  foot,  640 
of  hand,  305 
dorsal  or  intercostal,  376 
of  clitoris,  414,  426 
last,  529,  557,  602 
of  penis,  414,  440 
facial  (seventh  cranial),  61,  203 
femoral  cutaneous,  604 
fifth  cranial,  46,  201 
first  cranial,  198 
fourth  cranial,  50,  201 
frontal,  49,  56 
genitocrural,  532,  557 
glossopharyngeal  (ninth  cranial),  98,  204 
gluteal,  inferior,  552 
superior,  551,  616 
great  auricular,  75,  89,  90 
gustatory  (lingual),  iiS 
hemorrhoidal,  inferior,  413 
hypoglossal  (twelfth  cranial),  88,  206 

loop  (ansa  hypoglossi),  88 
hypoglossi  communicantes,  88,  89,  90 

descendens,  88,  90 
iliohypogastric,  450,  451.  53° 
cutaneous  branches,  602 
dorsal  of  penis,  440 
ilio-inguinal,  448,  451,  530,  557 
inferior  dental,  117,  150 
maxillary,  4S,  117 
pudendal,  406 
inframaxillary,  61,  74 
infra-orbital  (facial),  61 

plexus,  61,  151 
infratrochlear,  56 
intercostal,  350,  376,  451 
anterior  cutaneous  branches,  266,  451 
lateral  cutaneous  branches,  282,  451 
intercostohumeral,   266,   280,    282,    319, 

351,  365 
interosseous,  anterior,  317 
posterior,  293,  318,  386 


Nerve  or  nerves  :— 
Jacobson's,  206 
labial  (superior  maxillary),  151 
lachrymal,  50,  56 

laryngeal  inferior  or  recurrent,  104 
left,  342 

superior,  103 
larynx,  nerves  of,  146 
last  ilorsal,  529,  557,  602 
lingual  or  gustatory,  118 
lumbar,  376 

plexus,  529 
lumbosacral  cord,  551,  529 
malar  (facial),  61 

(superior  maxillary),  150 
masseteric,  117 
maxillary,  inferior,  48,  117 

superior,  48,  149 
median,  2S8,  298,  316,  317,  319 
mental,  68,  118 
meningeal  (glossopharyngeal),  206 

(hypoglossal),  206 

(inferior  maxillary),  117 

(pneumogastric),  103 

(superior  maxillary),  150 
motor  oculi  (third  cranial),  57,  200 
musculocutaneous  (arm),  288,  315,  319, 
378 

(leg),  588 
musculospiral,  290,  318,319,  365,  372,  378 
mylohyoid,  81,  118 
nasal,  56,  149 

(superior  maxillary),  151 

superior  (superior  maxillary),  152 
nasopalatine,  148,  152 
obturator,  534,  582 

accessory,  536,  583 
occipital,  great,  129 

small,  75,  89,  90,  129 

third,  129 
oculomotor  (third  crain'al),  57,  200 
oesophageal,  104,  342 
olfactory  (tract,  bulb,  nerves),  198 
optic  (second  cranial),  57,  197,  200 

(commissure,  tracts,  nerves) 
ophthalmic,  48,  54 
orbital  or  temporomalar,  150 

(Meckel's  ganglion),  151 
parotid,  66 
palatine,  anterior,  151 

external,  152 

posterior,  152 
palmar  cutaneous,  298,  301 
palpebral  (superior  maxillary),  151 
perineal,  414 
penis,  dorsal  nerve,  414 
petrosal,  great  or  deep,  46,  151 

superficial,  external,  203 
great,  151,  203 
lesser,  203 
pharyngeal,  103,  106 

plexus,  io5 
phrenic,  89,  100,  324 
plantar,  external,  642 

internal,  638 
plexus,  brachial,  312 

cardiac,  deep,  354 
superficial,  354 

carotid,  48,  106 

cavernous,  ic6 


670 


INDEX. 


Nerve  or  nerves  : — 
plexus,  cervical,  89 

Cruveilheir,  129 

dental,  superior,  150 

infraorbital,  151 

lumbar,  529 

oesophageal,  342 
'  pharyngeal,  98,  104,  125 

pulmonary,  342,  359,  360 

sacral,  551 

semilunar,  509 

solar,  509 
pneumogastric,  103,  206,  342 
popliteal,  external,  588,  618 

internal,  619 
pterygoid,  external  and  internal,  117 
pudendal,  long  or  inferior,  406,  604 
pudic,  internal,  413,  552 

in  female,  426 
pulmonary  plexus,  posterior,  341 ,  359, 360 
radial,  293,  318,  378 
recurrent  articular  of  popliteal,  619 
of  small  sciatic,  604 

laryngeal,  342 
rhomboid,  314 
sacral,  376,  551,  602 

cutaneous  filaments,  602 

fourth,  551 

plexus,  551 
saphenous,  external  or  short,  616 

internal  or  long,  534,  566,  588 
sciatic,  great,  553,  610 

small,  552,  602,  604 
second  cranial,  57,  200 
semilunar,  509 
septal  or  nasopalatine,  148,  152 

or  nerve  of  Cotunnius,  152 
seventh  cranial,  61,  203 
sixth  cranial,  57,  201 
Soemmering,  406 
solar,  509 

sphenopalatine,  149 
spinal,  376,  395 

accessory,  76,  91,  206 
splanchnic,  great,  lesser,  smallest,  345 
sternal,  76,  89,  91,  266 
stylohyoid,  61 
subclavian,  315,  319 
suboccipital,  136 
subscapular,  upper,  middle,  lower,  318, 

319     . 
superficial  cervical,  75,  89,  90 
supra-acromial,  76,  89,  91,  266,  365 
supraclavicular,  76,  89,  91,  266 
supramaxillary,  61 
supra-orbital,  25,  49 
suprascapular,  315,  319,  371 
suprasternal,  76,  89,  91,  266 
supratrochlear,  25,  49 
supply  for  abdominal  muscles,  453 
sympathetic  cord  and  ganglia,  cervical, 
io5 

lumbar,  526 

sacral,  553 

thoracic,  345 
temporal  (facial),  26,  61 
(inferior  maxillary),  117 
(superior  maxillary),  150 
temporofacial,  division  of  facial,  61 
temporomalar,  150 


Nerve  or  nerves  : — 
tenth  cranial  (pneumogastric),  103,  206, 

342 
third  cranial  (motor  oculi),  57,  200 
thoracic,  anterior,  external,  272,  315,  319 
internal,  316,  319 
posterior  or  long,  280,  315 
tibial,  anterior,  598 

posterior,  631 
trigeminal  (fifth  cranial),  46,  201 
trochlear  (fourth  cranial),  50,  201 
tympanic,  206 
to  abdominal  muscles,  453 
arachnoid,  156 
larynx,  146,  147 
muscles  of  larynx,  147 
obturator  internus,  552,  610 
ovary,  546 
pectineus,  56S 
penis,  414,  440 
pterygoideus,  externus,  117 

internus,  117 
pyriformis,  552 
quadratus  femoris,  612,  552 
trapezius,  89,  91 
ulnar,  288,  297,  29S,  316,  319 
Vidian,  151 

of  Wrisberg,  see  lesser  internal  cuta- 
neous, 316,  319,  365 
Ninth  cranial  nerve  (glossopharyngeal), 

98,  204 
Nipple,  255,  266 
Nose,  fossae  of,  14S 
meatuses  of,  148 
Notch,    interclavicular   or  suprasternal, 

255 
sciatic,  greater  and  smaller,  615 
supra-orbital,  25 
Nuck,  canal  of,  544 
Nucleus,  amygdaloid,  236 
caudate,  226 
dentate,  246 
lenticular,  228 
locus  niger,  240 
red,  240 

subthalamic  or  Luy's,  240 
Nutrient  artery  to  clavicle,  113 
artery,  of  femur  (third  perforating),  580 
of  fibula,  633 

of  humerus  (brachial),  287 
of  ilium,  612 

of  radius,  anterior  interosseous,  297 
of  tibia,  632 

of  ulna,  anterior  interosseous,  297 
Nymphae  (labia  minora),  423 


Obliquus  abdominis,  externus,  443 
internus,  447 

capitis,  inferior  and  superior,  134 

inferior  (eye),  58 

superior  (eye),  50 
Obliterated  hypogastric  arteries,  538,  547 
Obturator  artery,  547,  583 

accessory  nerve,  536,  583 

externus,  582 

fascia,  398 

internus,  6o5 
nerve  to,  610 


INDEX. 


671 


Obturator  nerve,  534,  582 

accessory,  536,  583 
Occipital  arter>%  95,  130 
bone,  external  protuberance  (crest),  18 

superior  curved  line,  18 
convolutions,   inferior,    middle,    supe- 
rior, 188 
inferior,  194 
lobe,  1S9 
convolutions  of,  1S9,  194 

referred  to  exterior  of  cranium,  24 
sulci  of,  24,  1S8 
nerves,  great,  129 
small,  75,  89,  90,  129 
third,  129 
protuberance,  external,  18 
sinus,  42 

sulci,  inferior  and  superior,  24,  188 
triangle,  84 
Occipitofrontalis,  25 

Occipitotemporal    convolution,    inferior, 
194 
superior,  192,  194 
Oculomotor  groove,  140 

nerve  (third  cranial),  57,  200 
CEsophageal  arteries,  112,  346,  509,  516 

nerves,  104,  342 
CEsophagus,  343 
Olecranon,  257 
Olfactory  bulb,  198 
lobe,  development  of,  170,  172 
nerve,  198 
sulcus,  194 
tract,  198 
Olivary  body,  248 
Omega  loop,  477,  501,  502 
Omental  arteries  (epiploic),  511 
Omentum.  472 
cavity  of  greater,  468,  470 
development  of  greater,  468 
gastrocolic  or  greater,  468,  470,  476,  483, 

494 
gastrohepatic,  lesser,  473,  492,  494 
gastrosplenic  or  third,  506 
Omohyoid,  79 
Opening,  femoral,  525 
in  adductor  magnus,  578 
Fallopian  tube,  544 
saphenous,  560 
superior  of  thorax,  323 
of  ureters  into  bladder,  548 
Openings  into  auricle,  left,  355 
right,  354 
in  diaphragm,  351 
into  nasal  fossae,  148 
into  stomach,  cardiac  and  pyloric,  494 
of  the  ducts  of  prostatic  glands,  550 
of  glands  of  Bartholin,  424 
Operculum,  1S6 
Ophthalmic  artery,  26,  53 
division  of  fifth  cranial  nerve,  48,  54 
ganglion,  56 
nerve,  4S.  54 

veins,  inferior  and  superior,  54 
Opponens  minimi  digiti,  309 

pollicis,  309 
Optic  chiasm  or  commissure,  197 
nerve,  57,  197,  200 
thalamus,  230 
development  of,  171,  173,  232 


Optic  thalamus,  commissure,  middle  and 
posterior,  232 
pulvinar,  230 
sulcus  choroideus,  230 
tubercle,  anterior,  230 
tracts,  197 
Orbicularis  oris,  63 

palpebrarum,  2S 
Orbit,  dissection  of,  48 
Orbital  artery,  62 
convolutions  of  frontal  lobe,  194 
fascia,  49 
sulcus,  192 

or  temporomalar  nerve,  150 
Orifice  of  ejaculatorj'  ducts,  550 
of  stomach,  cardiac,  pyloric,  494 
of  vagina,  424 
Os  calcis,  554 

uteri,  543 
Otic  ganglion,  119 

Outlining  on  exterior  of  body  the  shape 
of  the  brain,  18 
colon,  505 
heart  and  great  vessels, 

259 
intestines,  505 
liver,  491 

lungs,  and  fissures,  262 
spleen,  506 
stomach,  495 
Ovale  centrum,  majus  and  minus,  207 
Ovarian  artery,  518 
ligament,  543,  544 
lymphatics,  546 
plexus,  546 
veins,  521 
Ovarj',  544 
ligament  of,  543,  544 
lymphatics  of,  546 
nerves  of,  546 


Pacchionian  glands,  155 
Palate,  soft,  142 
Palatine  arteries,  95,  122 

arches,  anterior  and  posterior,  142 

nerv'es,  151,  152 
Palatoglossus.  144 
Palatopharyngeus,  143 
Palm,  dissection  of,  300 
Palmar  arch,  deep,  310 
superficial,  303 

fascia,  301 

nerves,  cutaneous,  298,  301 

synovial  sac  for  long  flexor  tendons,  311 
Palmaris  brevis,  300 

longus,  291 
Palpebral  arteries,  54 

fascia,  49 

nerves,  151 
Pampiniform  plexus,  female,  546 

male,  521 
Pancreas,  508 

development,  467 

duct  (Wirsung),  508 

jiosition  and  relations,  508 
Pancreatic  arteries,  510 

veins,  515 
Pancreatica  magna,  510 
Pancreaticae  parvae,  510 


672 


INDEX. 


Pancreaticoduodenalis    artery,    inferior, 
511 
superior,  511 
veins,  512 
Paracentral  lobe,  or  convolution,  186,  igi 
Parietal  convolution,  ascending,  inferior, 
superior,  186 
eminence,  18 
lobe,  186 
indicated  on  exterior  of  skull,  22 
Parieto-occipital  fissure,  184,  igo,  194 

on  exterior  of  skull,  22 
Parotid,  arterial  branches  to,  62 
fascia,  59,  13S 
gland,  66 

duct  of  (Stenson's),  65 
nerves,  66 
veins,  66 
Pars  bulbosa  of  urethra,  551 
Patella,  554 

ligament  of  (ligamentum  patellae),  576 
Pectineus,  565 
Pectoral  fascia,  268 
Pectoralis  major,  268 

minor,  274 
Peduncles  of  cereliellum,  ig6,  244 
of  cerebrum,  196 
of  corpus  callosum,  197,  210 
of  pineal  gland,  224 
Pelvic  fascia,  398  et  seq. 
viscera. 537 
dissection  of,  536 
Pelvis,  comparative  measurement  of  male 

and  female,  422 
Penis,  440 
angle,  440 
arteries  of,  dorsal,  superficial,  436,  573 

deep,  412,  413 
body,  440 
bulb,  415 
coverings,  442 
crura  of,  416 
dartos,  406,  415 
dissection,  435,  440 
elastic  sheath  of,  415 
glans,  415,  440 
neck,  415 
nerves,  dorsal,  deep,  414 

superficial,  440 
prepuce,  440 

suspensory  ligament,  406,  438,  440 
vein,  dorsal,  442 
Perforated  space,  anterior,  194,  196 

posterior,  197 
Perforating  arteries,  of  foot,  596,  643 
of  hand,  310 

of  internal  mammary,  321 
of  profunda  femoris,  579 
Pericardial  arteries,  345 

veins,  327 
Pericardium,  32S 
Perineal  arteries,  superficial,  412 
transverse,  412 
body,  431 
fascia,  deep  layer,  402,  403 

superficial,  deep  layer  (Colics'),  404 
nerves,  414 
triangles,  408,  427 
Perineum,  female,  422 
dissection,  424 


Perineum,  landmarks,  422 
male,  397 
dissection,  404 
landmarks,  397 
triangle  of,  408 
Peritoneal  ligaments  of  the  bladder,  477 
colon  (costocolic),  471,  477 
liver,  486 
rectum,  477 
spleen,  506 
stomach,  473,  494 
uterus,  478 
fossae,  473,  482 
reflections,  471,  483 
over  bladder,  537 
uterus,  543 
Peritoneum,  462 
development  of,  462 
divisions,  parietal,  visceral,  462 
ligaments,  473 
mesentery,  472 
omenta,  472 
line  of  attachment  to  posterior  abdom- 
inal wall,  470 
traced  in  section,  anteroposterior,  473 

transverse  sections,  478 
viscera,  covered  by,  482 
Peroneal  artery,  633 
anterior,  594 
posterior,  633 
nerve,  from  external  popliteal,  619 
vein,  633 
Peroneus,  brevis,  630 
longus,  630 
tertius,  590 
Pes  hippocampi,  214 
Petrosal  nerve,  deep,  great,  46,  151 
superficial,  external,  203 
great,  151,  203 
lesser,  203 
sinuses,  inferior,  superior,  42,  92 
Petrous  ganglion  (glossopharyngeal),  204 
Pharyngeal  aponeurosis,  124 
artery,  ascending,  96 
muscles,  125 
nerves,  103,  106 
plexus,  106 
tonsil,  142 
Pharynx,  124 
dissection  of,  141 
interior  of,  141 
muscles  of,  125,  143 
Phrenic  artery,  516 
nerve,  89,  100,  324 
vein,  inferior,  521 
Phrenocolic  ligament,  471,  477 
Phrenogastric  ligament,  473,  494 
Phrenosplenic  ligament,  506 
Pia  (brain),  156 
dissection  of,  165 
removal  of,  165 
(spinal),  392 
Pillars  (or  columns)  of  the  external  ab- 
dominal ring,  444 
of  the  fauces,  142 

of  the  fornix,  anterior  and  posterior, 
216 
Pineal  gland,  224 

development  of,  171 
Pituitary  gland,  197 


INDEX. 


673 


Pituitary  gland,  development  of,  171,  175 
Plantar  arch,  643 
artery,  digital,  640,  643 
collateral,  643 
external,  642 
internal,  640 
fascia,  634 

nerve,  external,  642 
internal,  638 
Plantaris,  621 
Platysnia  tnyoides,  70 
Pleuras,  323 

relation  to  the  chest  walls,  264 
Pleural  arteries,  346 
Plexus,  brachial,  312 
cardiac,  deep  and  superficial,  354 
carotid,  48,  106 
cavernous,  106 
cervical,  89 
Cruveilheir,  129 
dental,  superior,  150 
infraorbital,  151 
lumbar,  529 
oesophageal,  342 
pharyngeal,  98,  104.  125 
pulmonary  posterior,  342,  359,  360 
sacral,  551 
semilunar,  509 
solar,  509 

venous,  choroid  of  lateral  ventricle,  218 
fourth  ventricle,  220,  250 
third  ventricle,  220 
dorsal  of  foot,  5S6,  638 

of  hand,  37S 
hemorrhoidal,  40S 
ovarian,  546 
pampiniform,  female,  546 

male,  521 
prostatic,  418 
vesical,  420 
vesicoprostatic,  401 
Pneumogastric   (tenth   cranial),    103,  206, 

342 
Pomum  Adami  (Adam's  apple),  69 
"  Points,"  anatomical,  599 
"  Point,  McBurney's,"  501 

Sylvian,  18 
Pons,  196,  246 
development  of,  171,  175 
hepatis,  490 
Popliteal  arterj-,  623,  624 
nerve,  external,  588,  61S 

internal,  619 
space,  620 

dissection,  621 
landmarks  of,  599 
vein,  623 
Popliteus,  621 
Portal  vein,  492,  514 
Posterior  auricular  artery,  96 
circumflex  artery,  279,  372 
nares,  141 

scapular  artery,  112, 113,  370 
Pouch  of  Douglas,  431,  477,  483, 543 
glosso-epiglottic,  143 
rectovaginal,  483,  543 
rectovesical,  4S3 
uterovesical,  4S3,  543 
Poupart's  ligament,  434,  445,  554 
Precentral  sulcus,  195 

43 


Prepatellar  bursa,  558 
Prepuce  of  clitoris,  423 

of  penis,  440 
Princeps  cervicis,  artery,  130 

poUicis,  310 
Process,  acromion,  256 

angular,  external  (E.  A.  P.)  and  inter- 
nal, 18 

coracoid,  256 

malar,  24 

mastoid,  18 

olecranon,  257 

styloid  of  radius  and  ulna,  258 

vermiform  of  cerebellum,  242 

zygomatic,  18 
Processus  vaginalis  of  peritoneum,  460 
Profunda  artery  (brachial),  inferior  and 
superior,  287,  372 
cervicis  (deep  cervical),  113,  130,  135 

cervicis  vein,  iii,  136 

femoris  artery,  579 
vein,  574 
Pronator  quadratus,  64S 

radii  teres,  290 
Prostate,  420 

capsule  of,  401,  421 

ligament,  401 
Prostatic  glands,  opening  of  ducts,  550 

plexus,  venous,  418 

sinus,  550 

urethra,  550 
Protuberance,  external  occipital,  18 
Psoas  abscess,  525 

magnus,  527 

parvus,  528 
Pterygoid  artery,  121 

nerves,  117 
Pterygoideus  externus,  123 

internus,  124 
Pterygomaxillary  ligament,  123 
Pterygopalatine  artery,  122 
Pubes,  554 

body  of,  554 

spine  of,  554 

symphysis  of,  554 
Pubic  artery,  547 

portion  of  fascia  lata,  560 

spine,  554 
Puboprostatic  ligament,  402 
Pudic  artery,  external,  deep,  573 

superficial  or  superior,  557,  573 
internal,  411,  547 
in  female,  426 

nerve,  internal,  413,  552 
in  female,  426 

vein,  internal,  413 
superficial,  external,  436,  557 
Pudendal  nerve,  inferior,  406,  604 
Pudendum,  423 

Pulley  for  tendon  of  superior  oblique,  50 
Pulmonary  artery,  332 
left,  334 
right,  332 

plexus,  posterior,  341.  359,  360 

sinuses  (Valsalva),  356 

valves  (semilunar),  355 

veins  opening  into  left  auricle,  359 
Pulvinar  (optic  thalamus),  230 
Putamen  (lenticular  nucleus),  230 
Pyloric  artery,  510 


674 


INDEX. 


Pyloric  orifice  of  stomach,  494 

vein,  514 
Pylorus,  494 
Pyramidalis  abdominis,  453 

nasi,  29 
Pyramids  of  medulla,  248 
Pyriformis,  605 

fascia  of,  399 


Quadrate  lobe  of  cerebellum,  242 
cerebrum,  191 
of  liver,  490 
Quadratus  femoris,  607 

nerve  to,  552,  612 

lumborum,  528 

menti  (depressor  labii  inferioris),  63 
Quadriceps  extensor  femoris,  576 
Quadrigeminal  bodies,  224 

nates,  testes,  crucial  sulcus,  224 


Radial  artery,  in  forearm,  293 
in  the  hand,  310 
at  the  wrist,  3S7 
carpal,  anterior,  294 

posterior,  310 
recurrent,  294 
nerve,  293,  318,  378 
vein,  2S2,  378 
Radialis  indicis  artery,  310 
Radius,  nutrient  artery  to,  297 
Ranine  artery,  94 
Raphe  of  corpus  callosum,  210 
Receptaculum  chyli,  527 
Recess,  tonsilar,  142 
Rectal  artery,  inferior,  412 
middle,  547 
superior,  514 
tube,  objection  to,  506 
Rectovaginal  fossa,  477,  483,  543 
Rectovesical  fascia,  399,  538 

fossa,  477,  483 
Rectum,  lower  portion,  421 
upper  portion,  501,  504 
ligaments  of,  40X,  477 
Rectus  abdominis,  453 
sheath  of,  454 
ca))itis  anticus,  major  and  minor,  126 
lateralis,  126 

posticus,  major  and  minor,  134 
femoris,  565 
inferior  (eye),  58 
internus  (eye),  52 
superior  (eye),  52 
Recurrent  arteries,  interosseous,  386 
palmar  arch,  deep,  310 
radial,  294 

tibial,  anterior,  posterior,  594 
ulnar,  anterior,  posterior,  296 
nerves,  laryngeal,  342 
of  popliteal,  619 
of  small  sciatic,  604 
Red  nucleus,  240 

Reduplicated  fold  of  corpus  callosum,  208 
Reflections  of  peritoneum,  471,  483 
Regions  of  the  abdomen,  435 

of  the  face,  22 
Reil,  island  of  187 
Relations  at  the  elbow,  257 


Relations  behind  the  internal  malleolus, 

632 
Removal  of  arachnoid,  156 

of  brain,  36 

of  dura,  34 

of  fascia  lata,  562,  602 

of  deep  fascia  of  leg,  588,  618 

of  heart  and  lungs  from  thorax,  343 

of  palmar  fascia,  302 

of  pia,  165 

of  plantar  fascia,  636 
Renal  artery,  516 

vein,  521 
Restiform  body  (or  tract)  of  medulla,  244, 

254 
Retina,  central  artery  of,  53 
Retropharyngeal  abscess,  141 
Retzius,  space  of,  478,  537 
Rhomboid  nerve,  314 
Rhomboideus,  major  and  minor,  366 
Ribs,  how  to  count,  257 
Rima  glottidis,  145 

pudendi  or  genitalis,  423 
Ring,  abdominal  (inguinal),  external,  444 
internal,  456 
formation  of,  457 
"  Rings,"  so-called  anatomical,  446,  599 
Risorius,  59 
Rivinus,  ducts  of,  120 
Rolando,  fissure  of,  21,  182 
development  of,  177 
Root  of  lungs,  359 

of  penis,  440 
Rosenraiiller,  fossa  of,  142 
Rostrum  of  corpus  callosum,  196,  208 
Rotation  of  intestines,  464 
Round  ligament  of  liver,  488 

of  uterus,  544 
Rugae  of  vagina,  431 


Sac,  pleural,  323 

pericardial,  328 

peritoneal  (greater  omentum),  470 
Sacculations  of  large  intestine,  500 
Sacra  media,  518 
Sacral  arteries,  lateral,  548 
middle,  518 

nerves,  376,  551,  602 

plexus,  551 

sympathetic  cord  and  ganglia,  553 
Sacrolumbalis  (iliocostalis),  375 
Sacrosciatic  foramina,  greater,  smaller, 
615 

ligament,  great,  614 
small,  615 
Salivary  glands,  66,  85,  119 
Salpingopharyngeus,  145 
Saphenous  lymphatic  glands  (femoral), 

557 
nerve,  externa!  or  short,  616 

internal  or  long,  534,  566,  588 
opening,  560 

vein,  external  or  short,  586,  618 
internal  or  long,  557,  574,  586 
Sartorius,  562 
Scalenus   anticus,  medius,  posticus,  100, 

lOI 

Scaphoid  bone,  tubercle  of,  554 
Scapular  artery,  posterior,  112,  113,  370 


INDEX. 


675 


Scapular  artery-,  dorsal,  278,  371 
Scarpa,  fascia  of,  43S 

foraniitia  of,  152 

triangle  of,  56S,  570 
Sciatic  artery,  547,  613 

nerve,  great,  553,  610 
small,  532,  602,  604 

notch,  greater  and  lesser,  615 
Scrotum,  dartos,  406 
Second  cranial  nerve,  57,  200 
Semilunar  fold  of  Douglas,  450 

ganglion,  509 

valves,  355 
Semimembranosus,  609 
Seminal  vesicles,  420 
Semispinalis  colli,  135 
Semitendinosus,  609 
Septal  artery,  14S,  149 

nerve  (of  Cotunnius),  14S,  152 
Septum,  arachnoid,  392 

crural,  526 

lucidum,  214 
development  of  173 

pectiniforme,  416 
Serratus  magnus,  279 

posticus,  inferior  and  superior,  370 
Seventh  cranial  nerve,  61,  203 
Sheaths  of  long  flexor  tendons  in  palm, 
303 

of  rectus  abdominis,  454 
?Hin,  554 

Shortening,  measuring  for,  in  lower  ex- 
tremity, 434,  554 
in  upper  extremity,  256 
Shoulder,  cutaneous  nerves  of,  anterior, 
264 
posterior,  365 

dissection  of,  anterior,  272 
posterior,  360 

landmarks  of  256 
Sight,  center  of,  200 
Sigmoid  artery,  512 

flexure  of  colon,  477,  501,  502 

sinus  (lateral),  21,  40,  92 
Sinus,  cavernous,  43 

circular,  44 

confluence  of  (torculai   Herophili),  35, 
42 

coronary,  353,  354 

lateral,  21,  40,  92 

longitudinal,  inferior,  36 
superior,  20,  34 

marginal,  42 

of  Morgagni,  126 

occipital,  42 

petrosal  inferior,  42,  92 
superior,  42 

prostatic  (pocularis),  550 

straight,  40 

transverse,  44 

of  Valsalva,  3.56 
Sixth  cranial  nerve,  57,  201 
Skull,  interior  of  base,  3S 

dissection  of  interior,  44 

fossae  of,  anterior,  middle,  posterior,  38 
Small  intestines,  499 

occipital  nerve,  75,  89,  90,  129 

sacrosciatic  ligament,  615 

sciatic  nerve,  552,  602,  604 

center  of,  200 


Socia  parotidis,  66 

Soemmering,  nerve  of,  406 

Soft  palate,  142 

Solar  plexus,  509 

Soleus,  622 

Space,  anterior  elbow,  292 

axillary,  257,  268,  270,  275,  648 

of  Burns,  139 

interpeduncular,  198 

lunated  in  semilunar  valves,  355 

perforated,  anterior,  194,  196 
posterior,  197 

popliteal,  620 

of  Retzius,  47S,  537 

subarachnoid,  anterior,  154 
posterior,  155 
spinal,  392 

subdural,  32,  152 
spinal,  391 
Spermatic  artery,  518 

fascia,  external,  444 
formation,  460 
internal,  456 

plexus  (pampiniform),  521 

veins,  521 
Sphenoidal  fissure,  46 
Sphenopalatine  artery,  148 

(Meckel's)  ganglion,  151 
Sphincter  ani,  externus,  407 
internus,  422 

vaginae,  427 
Spigelian  lobe  of  liver,  490 
Spinal  nerves,  376,  395 
Spinal  accessory  nerve,  76,  91,  206 

arachnoid,  390 

canal  (central),  394 

cord,  392 
dissection  of,  3S9, 
fissure,  anterior  and  posterior,  394 

dura,  390 

muscles,  373 

nerves,  395 

posterior  branches,  376 

pia,  392 
Spinalis  dorsi,  374 

Spine  of  ilium,  anterior  superior,  554 
posterior  superior,  599 

of  pubes,  554 

of  scapula,  256 

of  tibia,  534 
Splanchnic  nerves,  great,  lesser,  smallest, 

345 
Spleen,  506 

development,  467 

ligaments,  506 

position,  506 

relations,  506 

size,  506 
Splenic  artery,  510 

flexure  of  colon,  477,  501,  503 

vein,  515 
Splenium  of  corpus  callosum,  207 
Splenius  capitis  et  colli,  131 
Spongy  portion  of  urethra,  550 
Stenson's  duct  (parotid),  66 

foramina,  149 
Sternal  artery  (internal  mammary),  321 

nerve,  76,  89,  91,  266 
Sternocleidomastoid,  76 
Sternohyoid,  80 


676 


INDEX. 


Sternoniastoid  artery  (occipital),  96 

(superior  thyroid),  93 
Sternothyroid,  80 
Stomach,  494 
fundus,  494 

impression  on  liver,  490 
openings,  cardiac  pyloric,  494 
position,  494 

relations  to  adjacent  organs,  494 
to  surface  of  body,  495 
Straight  sinus,  40 
Strise  acusticse,  252 

longitudinales,  210 
Styloglossus,  97 
Stylohyoid,  79 
Stylohyoid  ligament,  123 
Styloid  processes  of  radius  and  ulna,  258 
Stylomastoid  artery,  96 
Stylomaxillary  ligament,  123,  138 
Stylopharyngeus,  97 
Subanconeus,  369 
Subarachnoid  space,  anterior,  154 
posterior,  155 
spinal,  392 
tissue,  154,  392 
Subclavian  artery,  107 
left,  340 
nerve,  315,  319 
triangle,  84 
vein,  92,  99 
Subclavius,  272 
Subcrureus,  582 

Subcutaneous  nerves  of  the  abdomen,  436 
of  the  arm,  anterior,  283 

posterior,  365,  378 
of  the  back,  360 
of  the  chest,  264,  350 
of  the  face,  46,  61 
of  the  foot,  dorsum,  5S8,  598 

sole,  638,  642 
of  the  forearm,  anterior,  283 

posterior,  378 
of  the  gluteal  region,  602 
of  the  hand,  dorsum,  378 

palm,  298 
of  the  head,  anterior,  25,  46,49,  61,  75, 
129 
posterior,  129 
of  the  inguinal  region,  436 
of  the  leg,  anterior,  588 

posterior,  616,  619 
of  the  neck,  anterior,  75,  76 

posterior,  129 
of  the  perineum,  406,  413 
of  the  shoulder,  anterior,  264 

posterior,  365 
of  the  thigh,  anterior,  557 

posterior,  602 
of  the  thorax,  anterior,  264,  350 
posterior,  360 
Subdural  space,  32,  152,  391 
Sublingual  artery,  94 
duct  (of  Rivinus),  120 
gland,  119 
Submaxillary  arteries,  95 
duct  (Wharton's),  86 
ganglion,  119 
gland,  85 
trianglei^S2 
Submental  artery,  95 


Suboccipital  nerve,  136 

triangle,  132 
Subparietal  sulcus,  191 
Subscapular  artery,  278,  371 

nerves,  lower,  middle,  upper,  318,  319 
Subscapularis,  279 
Subthalamic  nucleus,  240 
Sulcus,  basilar,  246 
calcarine,  190,  194 
callosal,  191,  192 
central,  189 
choroideus,  230 
circular,  189 
collateral,  190,  194 
crucial,  224 
frontal,  inferior,   precentral,  superior, 

22,  185 
hippocampal  or  dentate,  190,  194 
intraparietal,  22,  186 
lateral  (crus  cerebri),  240 
medulla,  anterior,  248 ;  anterolateral,  248 

posterior,  252  ;  posterolateral,  252 
occipital,  inferior,  superior,  24,  188 
olfactory,  194 
orbital,  192 

parieto-occipital,  22,  184,  190,  194 
posterior  olivary,  248 
precentral,  195 
subparietal,  191 

temporal,   inferior,  194 ;   middle,  supe- 
rior, 24,  187 
Summary  of  the  development  of  the  ab- 
dominal viscera  and  perito- 
neum, 484 
Superficial  cervical  nerve,  75,  89,  90 

volar  artery,  294 
Superficial  fascia,  abdomen,  436,  438 
arm,  264,  282,  283 
back,  360,  362 
foot,  dorsum,  584 
forearm,  anterior,  282,  283 
gluteal  region,  600 
hand,  282,  360 
inguinal  region,  436,  438 
leg,  584 
neck, 360 
perineum,  404 
shoulder,  anterior,  264 

posterior,  360 
sole,  634 
thigh,  anterior,  556 

posterior,  600 
thorax,  anterior,  264 
posterior,  360 
Superior  curved  line  of  the  occipital  bone, 
18 
longitudinal  sinus,  20,  34 
oblique  muscle  (eye),  50 

(capitis),  134 
profunda  artery,  372,  387 
Supinator  brevis,  385 

longus,  292 
Supra-acromial    nerves,  76,  89,  91,  266, 

365 
Supraclavicular  nerves,  78,  89,  91,  266 
Suprahyoid  artery,  94 
Supramarginal  convolution,  186 
Supramaxillary  nerve,  61 
Supra-orbital  arch,  18 
artery,  18,  26,  53 


INDEX. 


677 


Supra-orbital  foramen,  68 

nerve,  25,  49 

notch,  25 
Suprarenal  arteries,  516 

bodies,  524 

veins,  521 
Suprascapular  artery,  112,  371 

foramen,  112 

ligament,  112 

nerve,  315,  319,  371 

notch,  112 

vein,  74,  99 
Supraspinatus,  366 
Suprasternal  nerves,  76,  89,  91,  266 

notch,  255 
Supratrochlear  nerve,  25,  49 
Sural  arteries,  624 

Suspensory  ligament,  clitoris,  406,  428 
duodenum,  498 
of  liver,  473,  486 
of  penis,  406,  43S,  440 
Sustentaculum  hepatis,  471,  476 

splenis,  471,  477 

tali,  554 
"  Sylvian  point  "  on  skull,  18 
Sylvius,  aqueduct  of,  240 
development  of,  176 
fissure  of,  21,  180,  194,  197 
Sympathetic  cords  and  ganglia,  cervical, 
106 
lumbar,  526 
sacral,  553 
thoracic,  345 
Symphysis  pubis,  554 

Synovial  membrane  of  the  palm  and  fin- 
gers, 311 


T/ENiA  semicircularis,  236 

tectae,  210 
Tail  of  caudate  nucleus,  228 
of  epididymis,  443 
of  pancreas,  50S 
Tapetum,  208 
Tarsal  arteries,  external  and  internal,  595 

ligaments,  external  and  internal,  29 
Tegmental  (red)  nucleus,  240 
Tegmentum,  240 
Tela  choroidea,  inferior,  220,  250 

superior,  220 
Temporal  artery,  26, 62 
anterior,  26, 
dee]),  .121 
middle,  62 
posterior,  26 
convolutions,  inferior,  middle,  superior, 

187,  194 
fascia,  30 
lobe,  187 

referred  to  exterior  of  cranium,  24 
muscle,  30 

nerves  (facial),  26,  61 
(inferior  maxillary),  117 
(superior  maxillary),  150 
auriculotemporal,  26,  117 
deep,  117 
sulci,  inferior,  194 
middle,  superior,  24,  187 
vein,  72 
Temporofacial  division  facial  nerve.  6i 


Temporomalar  nerve,  150 

Temporomaxillary  sinus  or  vein,  72 

Tendo-Achillis,  622 

Tetido-oculi,  2S.  29 

Tendon,  conjoined,  447 

Tendons  of  long  flexor  muscles  of  fingers 

in  palm,  311 
Tenon's  capsule,  49 
Tensor  palati,  144 

vaginae  femoris,  564 
Tenth   cranial    nerve     (pneumogastric), 

103,  206,  342 
Tentorium  cerebelli,  38 
Teres  major  and  minor,  368 
Testes  of  corpora  quadrigemina,  224 
Testicle  and  cord,  coverings  of,  442 
dissection  of,  443 
formation  of  same,  457 
Testicle,  442 
descent  of,  457 
dissection  of,  443 
gubernaculum  of,  457 
mediastiinim  of,  443 
mesentery  of  (mesorchium),  457 
tunica  albuginea,  443 
vaginalis,  443,  460 
Thebesius,  foramina  of,  354 

valve  of,  355 
Thecse  of  tendons  of  flexors  of  fingers, 

303 
Thigh,  dissection,  anterior,  556 
posterior,  600 
fascia  lata,  removal  of,  562,  602 
landmarks,  anterior,  432,  554 

posterior,  599 
superficial  arteries,  veins,  nerves,  557, 
602 
fascia,  556 
Third  cranial  nerve  (motor  oculi),  57,200 

ventricle,  222 
Thoracic  aorta,  338,  345 
artery,  278 
alar,  278 
long,  278 
superior,  276 
duct,  344 

nerves,  anterior,  external,  272,  315.  319 
internal,  316,  319 
posterior  or  long,  280,  315 
spinal  (intercostal),  350,  376,  451 
twelfth  or  last,  529,  557,  602 
opening,  superior,  323 
viscera,  334  et  seq. 
Thorax,  319 
dissection  of,  264 
interior,  319 
posterior.  360 
fascia  of  anterior,  26S 

Iiosterior,  360 
landmarks  of,  anterior,  255,  432 

posterior,  319 
mediastina,  322 
movements  of,  347 
opening  in,  superior,  323 
viscera  within,  334  et  seq. 
Thymus  gland,  324 
Thyro-arytenoid,  147 
Thyrohyoid,  So 

membrane,  146 
Thyroid  artery,  inferior,  iii 


678 


INDEX. 


Thyroid  artery,  superior,  93 
axis,  III 
gland,  114 
veins,  115 
TViyroidea  ima,  115 
Tibia,  nutrient  arterj-  of,  632 
malleolus  of,  554 
tuberosities  of,  554 
Tibial  artery,  anterior,  593,  594 
posterior,  631,  632 
recurrent,  594 
nerve,  anterior,  598 

posterior,  631 
veins,  593,  632 
Tibialis  anticus,  589 

posticus,  628 
Tissue,  subarachnoid,  154,  392 
Tongue,  142 

artery  of,  dorsal  (lingual),  94 
Tonsil,  lingual,  143 

pharyngeal,  142 
Tonsillar  artery  (facial),  95 
lobe  of  cerebellum,  242 
recess,  142 
Tonsils,  142 

Torcular  Herophili,  35,  42 
Trachea,  356 
Tracheal  artery,  112 
Trachelomastoid,  131,  375 
Tracts,  archiform,  external,  24' 
olfactory,  198. 
optic,  197,  200 
Transversalis  abdominis,  451 
cervicis,  135,  374 
artery,  112 
vein,'74,  99 
fascia,  454 
Transverse  aorta,  336 
of  basilar,  164 
cervical  artery,  112 

vein,  74,  99 
colon,  476,  501 
of  external  circumflex,  579 
facial  artery,  62 
fissure  of  brain,  180 
development,  176 
of  liver,  488 
mesocolon,  476 
perineal  artery,  412 
sinus,  44 
Transversus  pedis,  646 
perinsei,  deep,  416 
superficial,  410 
Trapezius,  362 
Treitz,  ligament  of,  498 
Triangle,  Hesselbach's,  457 
of  neck,  81 
anterior,  82 
carotid,  inferior,  83 

superior,  83 
lingual,  85 
occipital,  84 
posterior,  82 
subclavian,  84 
submaxillary,  82 
suboccipital, 132 
perineal,  408 
of  Scarpa,  568,  570 
Triangular  fascia,  446 
ligament,  deep,  402 


254 


Triangular  ligament,  superficial,  403 
space  at  base  of  bladder,  external.  420, 

450 
internal,  550 
Triangularis  sterni,  320 
Triceps,  369 
Tricuspid  valve,  355 
Trigeminal  nerve  (fifth  cranial),  46,  201 
Trigone,  external,  420,  540 

internal,  550 
Trigonum  habenulae,  232 

hypoglossi,  252 
Trochanter,  great,  554 
Trochlear  nerve  (fourth  cranial),  50,  201 
Trolard,  vein  of,  165 
Tubal  eminence  of  Eustachian  tube.  142 
Tube,  Eustachian,  141,  145 

Fallopian, 543,  544 

rectal,  objection  to,  506 
Tuber  cinereum,  196,  197 

development  of,  175 
Tubercle  of  Lower,  355 
deltoid,  256 

of  optic  thalamus,  anterior,  230 

of  scaphoid,  554 
Tuberculum  acusticum,  252 
Tuberosity  of  humerus,  256 

of  ischium,  554,  599 

of  tibia,  554 
Tunica  albuginea,  of  testicle.  443 

vaginalis,  of  testicle,  443,  460 
Twelfth  cranial  nerve.  88,  206 

or  last  dorsal  (intercostal),  529.  557.  602 
Tympanic  artery,  120 

nerve  (Jacobson's),  206 


Ulnar  artery,  in  the  forearm,  295 
in  the  hand,  304 
carpal  branches  of,  anterior,  297 

posterior,  297,  388 
recurrent,  anterior  and  posterior,  296 
nerve,  2S8,  297,  316,  319 
vein,  anterior,  282 
common,  282 
posterior,  2S2,  378 
Umbilical  arteries  (obliterated   hypogas- 
tric), 538,  547 
fissure  of  lirer,  490 
ring,  434 
vein,  490 
Uncinate  convolution,  191,  192,  194 
Upper  extremity  and  thorax,  landmarks 
of,  255 
posterior.  360 
measuring  for  shortening,  256 
Urachus,  538 
Ureter,  524,  540 
calices,  relations,  sinus,  524 
course,  length,  relations,  size,  540 
openings  of,  548 
Urethra,  dissection  of  interior,  548 
female,  431 
male,  5,=;o 
fossa  navicularis,  551 
lacunae,  551 

membranous  portion,  550 
pars  bulbosa.  551 
prostatic  portion,  5,50 
spongy  portion,  550 


INDEX. 


679 


Urethral  triangle  (perineal),  408 
Urinary  bladder,  537,  54S 
meatus,  external,  female,  424 
male,  4I5>  55' 
internal,  54S 
Urine,  course  of  extravasated,  404,  438, 

440 
Uterine  artery,  547 

plexus  (venous),  420 
Utero-inguinal  ligament  (round),  544 
Utero-ovarian     ligament     (ligament     of 

ovary),  543,  544 
Uteropelvic  ligament  (broad),  47S,  543 
Uterovesical  ligament  (anterior),  543 

pouch  or  fossa,  477,  4S3,  543 
Uterus,  543 
body,  cervix,  isthmus,  543 
ligaments,  broad,  477 
round,  544 
peritoneal,  543 
lymphatics,  546 
nerves  of,  546 
position,  relations,  size,  543 
Uterus  masculinus,  550 
Uvula,  142 


Vagina.  430 

bulb  of,  427 

orifice  of,  424 

relations  of,  430 
Vaginal  arteries,  547 

ligaments  (fingers),  303 

lymphatics,  546 

plexus  (venous),  420 
Vagus   (pneumogastric)   nerve,  103,  206, 

342 
Vallecula  of  cerebellum,  242 
Valsalva,  sinuses  of,  356 
Valve,  Eustachian,  355 

ileocecal,  499 

mitral  (bicuspid),  356 

semilunar,  35s 

Thebesius,  355 

tricuspid,  355 

of  VMeussens,  244 
Vas  deferens,  542 

ampulla,  course,    ejaculatory    duct, 
length,  relations,  sizei  542 

artery  of,  547 
Vasa  brevia,  510 

intestini  tenuis,  512 

veins,  515 
Vastus  externus,  575 

internus,  575 
Vein  or  veins  ; — 

acromiothoracic,  270 

anastomotic  of  Trolard,  165 

angular,  62 

of  arm  and  forearm,  2S2,  378 

ascending  (lumbar),  521 

axillary,  99,  275 

azygos  major  and  minor,  348 
left  superior,  350 

basilic,  283 
median,  283 

brachial,  286 

bronchial,  359 

cardiac,  353 

cephalic,  256,  269,  283 


Vein  or  veins  : — 
cephalic,  median,  283 
cerebral,  deep,  220 

choroid,  222 

Galen,  222 

corpus  striatum,  220 
superficial  or  cortical,  165 
anastomotic  vein  of  Trolard,  165 
basilar,  165 
inferior,  165 
middle,  165 

posterior  anastomosing  vein  of  Labbe, 
165 

superior,  165 
cervical,  deep  (profunda  cervicis),  iii, 
136 

transverse  (cervicis),  74,  99 
choroid,  222 
circumflex,  iliac,  deep,  520 

superficial,  436,  537,  572 
coronary,  553 
corpus  striatum,  220 
cystic.  514 
dorsal  of  penis,  442 

superficial,  440 
epigastric,  deep,  520 

sui)erficial,  436,  557 
facial,  62 

in  neck,  74 
femoral,  574 

deep  (profunda  femoris),  574 

subcutaneous  or  superficial,  557 
of  foot,  anterior,  586 
forearm,  378 
of  Galen,  222 

common,  40,  222 
ganglionic  or  deep  cerebral  or  central, 

220 
gastric,  514 

gastro-epiploic,  512,  514 
gluteal,  54S 
of  heart,  353 
hemorrhoidal,  408 

plexus,  408 
hepatic,  521 
iliac,  common,  520 

external,  520 

internal,  548 

deep  circumflex,  520 

superficial  circumflex,  557 
innominate,  92.  326 
intercostal.  34S 

left  superior,  350 

right  superior,  350 
interventricular,  anterior  and  poster- 
ior, 3.S3 
jugular,  anterior,  74,  99 

external,  74,  99 
jugular,  internal.  92 

posterior,  external,  74 
of  Labb6,  165 
leg.  586,  618 
lumbar,  541 

mammary,  internal,  327 
maxillary,  internal,  72 
median.  282 

basilic,  283 

cephalic,  2S3 
mediastinal.  327 
mesenteric,  inferior,  514,  515 


680 


INDEX. 


Vein  or  veins  : — 
mesenteric,  superior,  512,  514 
of  neck,  74 

oblique,  of  Marshall,  353 
obturator,  548 

ophthalmic,  inferior  and  superior,  54 
ovarian,  521 
pampiniform  (plexus),  male,  521 

female,  546 
pancreatic,  515 
pancreaticoduodenalis,    inferior    and 

superior,  512 
parotid,  66 
of  penis,  442 
pericardial,  327 
peroneal,  633 
phrenic,  inferior,  521 
popliteal,  623 
portal,  492,  514. 
profunda  cervicis,  iii,  136 

femoris,  574 
prostatic  (plexus),  418 
pudic,  internal,  413 

external,  superficial,  436,  557 
pulmonary,  359 
pyloric,  514 

posterior,  378 
radial,  282 
renal,  521 
saphenous,  external  or  short,  586,  618 

internal  or  long,  557,  574,  586 
spermatic  (pampiniform  plexus),  521 
splenic,  515 
subclavian,  92,  99 
superficial  epigastric,  557 

of  aim  and  forearm,  282 

of  forearm  and  hand,  posterior,  378 

of  thigh,  557 
suprarenal,  521 
suprascapular,  74, 99 
temporal,  72 

temporomaxillary  sinus,  72 
thyroid  gland,  115 
tibial,  anterior,  593 

posterior,  632 
transverse,  cervical,  74,  99 
Trolard,  vein  of,  165 
ulnar,  anterior,  282 

common,  282 

posterior,  282,  378 
uterine,  420 
vaginal  plexus,  420 
vasa  brevia,  515 
vertebral,  iii,  136 
vertical  (lumbar),  521 
vesical  (plexus),  420 
vesicoprostatic  (plexus),  401 
Velum  interpositum,  218 

development,  177 
Vena  azygos,  major  and  minor,  348 

sinistra,  superior,  tertia,  350 
cava,  inferior,  354,  520 

fissure  in  liver  for,  490 

superior,  327 
Ventricle,  fifth,  216 

development,  173 
fourth,  250 


Ventricle,  fourth,  development,  171,  176 
lateral,  210 
development,  170 
dissection  of,  214 
third, 222 
development,  171 
dissection  of,  222 
floor  of,  198 
Ventricles  of  heart,  355,  356 

of  larynx,  146 
Vermiform  appendix,  476,  500 

process  of  cerebellum,  242 
Vermis,   inferior  and  superior  (cerebel- 
lum), 242 
Vertebral  aponeurosis,  373 
artery,  no,  158 
muscles,  373 
vein.  III,  136 
Vertical  lumbar  vein,  520 
Verumontanum,  550 

Vesical  arteries,  inferior,  middle, superior, 
546 
plexus  (venous),  420 
Vesicles,  cerebral,  169 

seminal,  420 
Vesicoprostatic  plexus  (venous),  401 
Vesiculas  seminales,  420 
Vestibule  of  vagina,  424 
Vicq  d'Azyr,  bundle  of,  238 
Vidian  artery,  122 
canal,  151 
nerve,  151 
Vieussens,  valve  of,  244 
Villi,  arachnoidal,  155 
Viscera,  abdominal,  486 

covered  by  peritoneum,  482 
summary  of  development,  484 
cranial,  166 
pelvic,  537 
thoracic,  321 
Vitello-intestinal  duct,  471 
Vocal  cords,  true  and  false,  145 
Volar  artery,  superficial,  294 
Vulva,  423 


Weight  of  brain,  648 

Wharton's  duct,  86 

"  White  line  "  of  obturator  fascia,  399,  400 

Willis,  circle  of,  158,  161 

cords  of,  34,  35 
Winslow,  foramen  of,  470,  478 
Wirsung,  duct  of,  508 
Womb,  or  uterus,  543 
Wrist,  annular  ligament  of,  anterior,  302 
posterior,  378 

dissection  of  anterior,  300 
posterior,  376 

landmarks  of,  258 


Xiphoid  appendix,  432 


ZiNN,  ligament  of,  52 
Zygomatic  arch,  18 
Zygomaticus,  major  and  minor,  59 


COLUMBIA  UNIVERSITY  LIBRARIES  (hsistx) 

QM  28  H33  C.I 

A  maim, I!  n'  .iiMJu'iiu 


2002157292 


U^^ 


;--?!^5^ 


